Some standard content:
GB/T 4756-1998
This standard is equivalent to the international standard ISO3170:1988 "Manual sampling method for petroleum liquids" to revise GB/T4756-84 (91).
The differences between this standard and ISO3170 are:
1. In 5.4 of this standard, the specific contents of the installation position and installation method of the sampling head in ISO3171:1988 "Automatic pipeline sampling method for petroleum liquids" are quoted.
In 8.1 of this standard, the contents of 8.1 and 14.8 of APIMPMS (American Petroleum Institute Manual of Petroleum Measurement Standards) on the importance of automatic pipeline sampling method are added. 2. This standard has changed the following contents according to the actual situation in my country: a) The meaning of the definition in 3.8.1, the provisions of "within the repeatability range of the mean value" in 7.3.3 railway tank car, 7.3.4 road tank car and 8.2.1 have been changed.
b) Added "(For crude oil and heavy oil, the bottom free water should be released first)" in 4.2; added the provisions on sampling interval in 7.5 pipeline sampling.
This standard replaces GB/T4756-84 (91) from the date of implementation. This standard is proposed by China Petrochemical Corporation. This standard is under the technical jurisdiction of Petrochemical Research Institute of China Petrochemical Corporation. This standard was drafted by Petrochemical Research Institute of China Petrochemical Corporation. Drafter of this standard: Jin Dexi.
This standard was first issued in November 1984 and reviewed and confirmed in March 1991. 47
GB/T4756-1998
ISOForeword
This international standard should be used in conjunction with ISO3171 "Automatic pipeline sampling method for petroleum liquids". The purpose of this International Standard is to standardize the conditions for taking samples of liquid or semi-liquid hydrocarbons from tanks, drums or pipelines. If the hydrocarbon samples taken show obvious inhomogeneities in composition or in the content of water and sediment, the samples taken manually should not be expected to be representative, but they can be used to evaluate the degree of heterogeneity of the material and to estimate its quality and quantity. It should be recognized that in many countries some or all of the provisions covered by this International Standard are mandatory regulations under the laws of those countries and such regulations must be strictly followed. In the event of a conflict between such regulations and this International Standard, the former shall prevail. 48
1 Scope
National Standard of the People's Republic of China
Petroleum liquids—Manual sampling
Petroleum liquids—Manual samplingGB/T 4756 - 1998
eqv ISO 3170:1988
Replaces GB/T 4756--84(91)
1.1 This standard specifies the method for obtaining samples of liquid hydrocarbons, tank residues and sediments by manual method from fixed tanks, railway tank cars, road tank cars, tankers and barges, barrels and cans, or from pipelines carrying liquids (see 4.3). 1.2 This standard applies to the sampling of liquid petroleum products, crude oil and intermediate products stored in tanks or transported by pipelines. The pressure in the tanks should be at or near atmospheric pressure. The petroleum or liquid petroleum product being sampled should be liquid at temperatures close to ambient temperature up to 100°C.
The sampling methods specified in this standard are not applicable to the sampling of special properties of special petroleum products. The sampling of special properties of such petroleum products should be carried out in accordance with the provisions of other relevant standards. For example, there are corresponding special requirements for the sampling of electrical insulating oil, liquefied petroleum gas, liquefied natural gas, asphalt and chemical products, and unstable crude oil with a Reid vapor pressure higher than 180 kPa (1.8 bar). 1.3 The two basic manual sampling methods are:
a) tank sampling;
b) pipeline sampling.
When a batch of oil products is received or shipped, either tank sampling or pipeline sampling, or both, is used. If both methods are used, the two sets of samples obtained should not be mixed. 1.4 This standard also specifies methods to reduce or eliminate the loss of light components in the sample. The above losses may occur during sample handling or transfer, making the sample unrepresentative.
1.5 If methods suitable for taking representative samples of homogeneous petroleum liquids in storage or in transit are used to take samples of inhomogeneous liquids that differ significantly in composition and in the amount of sediment and/or water, the resulting sample may not be representative. 1.6 The sampling methods specified in this standard are suitable for taking samples for the following purposes: a) determining the quality of the oil;
b) determining the amount of water in the oil;
c) determining other contaminants in the transferred liquid. If the sampling conditions for purposes a), b), and c) conflict, separate sampling must be done. 1.7 This standard also specifies sampling methods for determining the degree of heterogeneity of inhomogeneous oil products in tanks and for estimating their quality and quantity. 1.8 This standard also covers sampling methods for residues and sediments in tanks and sampling techniques for liquid hydrocarbons under inert gas pressure. 2 Referenced Standards
The following standards contain provisions that are incorporated by reference into this standard. Unless otherwise expressly specified in the standard, the following referenced standards shall be the currently valid standards.
GB/T1884 Laboratory determination of density and relative density of crude oil and liquid petroleum products (densitometer method) GB/T6533 Determination of water and sediment in crude oil (centrifugation method) Determination of water content in crude oil (distillation method) GB/T 8929
Approved by the State Administration of Quality and Technical Supervision on June 17, 1998 and implemented on December 1, 1998
3 Definitions
This standard adopts the following definitions.
3.1 Competent person GB/T4756
—1998
A person who, through training, is able to discover the faults or shortcomings of a device or equipment based on experience, theory and practical knowledge, and can make authoritative judgments on the possibility of its improved use. Note 1: This person should have sufficient authority to ensure that his suggestions play a necessary role. 3.2 Integrity of the sample The sample is in an intact state without being altered, that is, the sample is stored with the same composition as when it was taken from the bulk liquid. 3.3 Mixer
A device that keeps the liquid in a pipe or container uniformly mixed in order to obtain a representative sample. 3.3.1 Static mixer
A mixing device without moving parts installed in a pipe or pipeline. The energy required to mix the liquid comes from the kinetic energy of the moving liquid.
3.4 Pipeline
Any section of a pipeline used to transport liquid. An unobstructed pipeline does not have any internal accessories, such as static mixers or orifice plates. 3.5 Residues and deposits Residues and deposits Organic or inorganic substances separated from oil and water and dispersed in water. a) Substances that fall from the liquid to the bottom of the tank; b) Substances that remain in the tank after the liquid in the tank is drained. 3.6 Sample conditioning When preparing the sample for analysis, it must be homogenized and become a stable sample. 3.7 Sample handling samplehandling
refers to sample preparation, transfer, division and transportation. It includes the transfer of samples from samplers (receivers) to containers and from containers to laboratory instruments for analysis. 3.8 Sample types sample types
3.8.1 All-levels sample A sample obtained when the sampler passes through the entire liquid layer in one direction so that it is filled with about three-quarters (maximum 85%) of the fluid. 3.8.2 Bottom sample bottom sample
A spot sample obtained from the material on the bottom surface (bottom plate) of the tank or container (see Figure 1). 3.8.3 Composite sample composite sample
A sample representing the entire material obtained by combining several spot samples in a specified proportion. The general type of composite sample is a combination of one of the following (see Chapter 4 and 7.3.1.1.2): a) Combine the upper sample, middle sample and lower sample in equal proportion; b) Combine the upper sample, middle sample and outlet liquid surface sample in equal proportion; c) A series of spot samples taken from more than 3 liquid surfaces of non-homogeneous oil products, and blend them in proportion to the amount of oil products they represent;
d) Individual samples taken from several oil tanks or tanker holds, each of which is proportional to the total amount of oil contained therein; e) A series of spot samples of equal volume taken from the fluid in the pipeline at specified intervals. Instructions for use:
1) Since ISO3170:1988 does not specify "should be filled to about three quarters (maximum 85%)", it is difficult to operate in practice. Here, the provisions in 3.1.4 of ASTMD1057--88 "Manual Sampling Method for Petroleum and Petroleum Products" are adopted. 50
GB/T 4756-- 1998
3.8.4 Representative sample A sample whose physical or chemical properties are the same as the volume average properties of the total volume sampled. 3.8.5 Running sample
A container is lowered from the top of the oil product to the bottom and then raised to the top of the oil product at the same speed. The container should be about three-quarters full when the liquid surface is raised. The sample obtained in this way is a routine sample. 3.8.6 Spot sample
A sample obtained from a pipeline at a specified position in the oil tank or at a specified time during pumping operation. 3.8.7 Suction-level sample A sample obtained from the lowest liquid level of the liquid output from the oil tank. When determining this liquid level, appropriate tolerances may be allowed for tank accessories such as rockers, withdrawal baffles or internal elbows (see Figure 1). 3.8.8 Upper sample
A sample taken at a liquid level one-sixth of the depth below the top surface of the petroleum liquid (see Figure 1). 3.8.9 Middle sample
A sample taken at a liquid level one-half of the depth below the top surface of the petroleum liquid (see Figure 1). 3.8.10 Lower sample
A sample taken at a liquid level five-sixths of the depth below the top surface of the petroleum liquid (see Figure 1). 3.8.11 Top sample
A spot sample taken 150 mm below the top surface of the petroleum liquid (see Figure 1). 3.8.12 Skim sample (surface sample) A sample taken from the surface of the petroleum liquid (see Figure 1). 3.9 Statistical terms terms 3.9.1 AQL (acceptable quality level) AQL (acceptable quality level) Maximum percentage of defective products (or the maximum number of defective products per 100 units). For sampling inspection, it can generally be considered satisfactory as a process average.
3.9.2 batch
The total number of packaged products of the same type and composition and produced or delivered in the same batch. 3.9.3 package
Any type of container, such as barrels, cans, cans or bottles. 3.9.4 percentage of defective products defective The number of defective units contained in any given number of product units divided by the total number of product units and multiplied by 100, that is: defective percentage -
3.9.5 Sample sizesamplesize
Number of defective units
Total number of product units
The number of samples to be drawn from a batch of products to determine the acceptability of the batch according to a given sampling plan. 3.10 Ulliage
For this standard, it refers to the empty volume left above the surface of the liquid in the sample receiver or container, expressed as volume. 3.11 Waterwater
3.11.1 Dissolved waterdissolved waterbzxz.net
Water present in oil that forms a solution with oil at room temperature. 3.11.2 Suspended water water Water suspended in oil in the form of fine droplets. Note 2: Over a period of time, it can aggregate into free water or dissolved water, depending on the intensity and pressure at the time. 3.11.3 Free water
GB/T 4756
6—1998
A layer of water that exists separately from the oil, typically located below the oil layer. 3.11.4 Total water
The sum of dissolved water, suspended water and free water in petroleum cargoes. 4 Sampling principles
4.1 In order to ensure that the sample used for evaluation is as representative as possible of the sampled oil, necessary precautions are given. These precautions are based on the characteristics of the liquid, the oil tank, container or pipeline being sampled, and the nature of the test to be performed on the sample. 4.2 Tank sampling can only be carried out when the oil in the tank is still (for crude oil and heavy oil, the bottom free water should be released first)2). Oil analysis is usually carried out by taking one of the following samples:
a) upper, middle and lower samples;
b) upper, middle and outlet surface samples. If the tests on these samples show that the oil in the tank is homogeneous, the samples can be combined in equal proportions and the next test can be carried out.
If the tests on these samples show that the oil in the tank is heterogeneous, samples must be taken at more than three surfaces and a composite sample prepared for analysis. If blending will compromise the integrity of the sample, each sample is analyzed separately and the proportion of the oil represented by each sample is calculated.
Other methods are:
c) routine sample;
d) full-layer sample.
4.3 In order to obtain representative samples from a batch of heterogeneous material conveyed in a pipeline, samples should be taken using an automatic sampling device. Sometimes, manual sampling may be necessary. However, these are spot samples, which may not be representative of the entire batch of material. 5 Instruments
5.1 General
The design and construction of the sampling equipment shall ensure that the original characteristics of the oil are maintained. The equipment shall have sufficient strength and external protection to withstand the normal internal pressure generated, or be equipped with a safety valve that is strong enough to withstand any treatment it may encounter. Before use, the cleanliness of the equipment should be confirmed.
Note 3: Various sampling equipment are generally described in 5.2 to 5.7, and some basic types are specified, but no detailed specifications are given, because any suitable equipment of the various types in 5.2 to 5.7 can be used. 5.2 Tank Samplers
5.2.1 Classification
Tank samplers are classified according to the samples taken as follows: spot sampling;
a bottom sample;
a tank sediment or residue sample;
routine sample;
full layer sample.
In order to lower and raise the sampling device in the oil tank, a rope or chain made of conductive, non-sparking material should be used. Note 4: The rope should be a good conductor that does not generate static electricity. 5.2.2 Point sampler
Instructions for use:
2) The content of GB/T4756·84 (91) "Methods for sampling petroleum and liquid petroleum products (manual method)" is retained. 52
GB/T 4756-1998
These sampling devices should be able to take samples at any specified liquid level in the tank. The following types of devices can be used. 5.2.2.1 Sampling cage
It is a metal or plastic holder or cage that can hold a suitable container. After assembly, it should be weighted so that it can sink quickly into the oil to be sampled and fill the container at any required liquid level (see Figure 2). For volatile products, it is best to use a sampling cage with a bottle of appropriate size in it to avoid loss of light components, because when transferring the sample from the added sampler to other containers, light component loss may occur. Note 5: If the sample bottle can be firmly selected on the weighted sampling rope, the sampling cage can be omitted. In this case, the bottle stopper should be tied to the sampling rope about 150mm from the sample neck.
5.2.2.2 Weighted sampler (see Figure 3) The sampler should be weighted so that it can sink rapidly into the sampled oil. If the sampler is used to take upper, middle, lower and outlet level samples, the sampler should be tied to a descending device and the sampler plug should be opened by pulling the descending device suddenly. If it is used for routine sampling, the special plug shown in Figure 4 should be used. In order to avoid cleaning the sampler after each sampling, all weighted materials should be fixed to the outside of the sampler so that they do not come into contact with the sample. Some samplers have special opening devices, such as a device that can open and close the valve at any required liquid level, which is guided by a hanging steel rope and lowered by a weight, or a wing valve or flap valve that can be closed when the sampler starts to move upward. 5.2.2.3 Interface sampler
It is made of a glass, metal or plastic tube with two ends open, which can flow freely through the liquid when it descends through it. The lower end of the sampler may be closed at the desired level by: a) a closing mechanism activated by the upward movement of the sampler; b) a closing mechanism activated by the descent of a weight guided by a suspension cable (drop sling). Interface samplers may be used to take spot samples from a selected level or to take bottom samples for the presence of contaminants. Interface samplers shall be used to collect a vertical column of liquid on the tank bottom or at any other selected level when slowly lowered (see Figure 5). 5.2.3 Bottom samplers
Samplers which open a valve or similar shutter by contact with the tank floor when lowered to the tank bottom and which close the valve or shutter when leaving the tank bottom (see Figure 6) are available. 5.2.4 Residue or sediment samplers
5.2.4.1 Grab samplers
This sampler is a solid brass box with a grab mechanism, the bottom of which is a set of two spring-closed clips, the sampler mechanism being released by the sling. Two light plate covers on the sides of the sampler are intended to prevent the sample from being washed out when the sampler is lifted from the liquid (see Figure 7).
5.2.4.2 Gravity or ram tube sampler
This is a tubular device of uniform diameter that is weighted or equipped with a mechanical operating device to penetrate the sediment layer to be sampled. 5.2.5 Routine sampler
The routine sampler is a container that is weighted or placed in a weighted sampling cage and, if necessary, may be equipped with a restricted filling fitting (see Figure 4). The sample is obtained by descending and ascending through the oil product (see Figures 2 and 3), but it cannot be determined that it is filled at a uniform rate. 5.2.6 Full-layer sampler
This sampler has a liquid inlet and a gas outlet and obtains the sample by descending and ascending through the oil product, but it cannot be determined that it is filled at a uniform rate. An example of a sampler is shown in Figure 8. 5.2.7 Gas lock device
This device is used to take samples from pressure tanks, especially those oil tanks using an inert gas system. It has a gas-tight shell mounted on the top of the valve, and the connection to the tank top is shown in Figure 9. The sample container or the special sampler shown in Figure 9, which is mounted in the sampling cage, is fastened to the lowering gear through the gas-tight window. The window is then closed, the top valve is opened, the sample container or sampler is lowered to the required depth in the product, filled with sample, and the sampler is raised. The valve must be closed before the sampler is removed through the window. 53
5.3 Drum and listening sampler
GB/T 4756-- 1998
Figure 10 shows a commonly used tubular sampler. This is a tube made of glass, metal or plastic, which can be equipped with suitable fittings to facilitate operation if necessary. It can be inserted into a barrel, can or road tanker at the required liquid level to extract a spot sample or into the bottom to extract a bottom sample to check for the presence of contaminants. A tubular sampler with a closing mechanism at the lower end can also be used to take a representative sample through a vertical cross section of the liquid.
Alternatively, a small sampling cage, a drum pump or a siphon device of suitable size can be used instead. 5.4 Pipeline Sampler
The pipeline manual sampler consists of a suitable pipeline sampling head and an isolation valve group. The sampling head should be installed in a vertical pipeline and its opening diameter should not be less than 6mm. The opening of the sampling head should face the direction of liquid flow and the distance from its sample entry point to the inner wall of the pipeline should be greater than 1/4 of the inner diameter of the pipeline (see Figure 11b)]. The shortest distance from the location of the sampling head to the upstream elbow is 3 times the inner diameter of the pipeline, but preferably not more than 5 times the inner diameter of the pipeline, and the shortest distance from the downstream elbow is 0.5 times the inner diameter of the pipeline. If the sampling head is installed in a horizontal pipeline, it should be installed on the pump output side. The distance from the sample entry point to the inner wall of the pipeline is shown in Figure 11a). The distance from the sampling head to the pump outlet is 0.5 to 8 times the inner diameter of the pipeline. The sampler should have an oil delivery pipe, the length of which should reach the bottom of the sample container so that it can be immersed in oil. 3.5.5 Containers
The sample container should be a glass bottle, a plastic bottle, a bottle with a metal cap or a can. Its application depends on the nature of the sampled material. The volume of the above containers is generally 0.25~~5L, but larger containers can also be used when special tests, large samples or progressive subdivision of samples are required. Plastic containers cannot be used to store samples because they cannot maintain the integrity of the sample due to diffusion. In addition, containers made of non-linear polyethylene can cause sample contamination and (or) sample container damage. 5.6 Container closures
Corks, frosted glass stoppers, plastic or metal screw caps can be used to close sample bottles. Rubber stoppers should not be used. The cork should be of good quality and should not contain loose pieces or dust. The cork should be softened by rolling or squeezing so that it can be pressed well into the neck of the bottle to prevent leakage or evaporation of the sample. If necessary, a protective cover of suitable material should be used. Volatile liquids should not be used with corks because their vapors will penetrate the cork and cause sample contamination. In this case, an inert gas seal should be used. Corks should not be reused for different types of products because it is difficult to thoroughly clean the cork after hydrocarbons have penetrated, which can cause contamination of subsequent samples. The reuse of corks is limited to the same type of product. The screw cap of the can or bottle should be equipped with a gasket of cork or other oil-resistant material. The gasket can be used only once and should be removed before cleaning the screw cap and a new gasket should be installed after cleaning.
5.7 Sample Cooler
The cooling coil is made of seamless copper tube or other suitable metal tube with an inner diameter of 6~10mm and fixed in an open portable container. When used, it should be completely immersed in an ice-water mixture. The inlet end of the pipe should be equipped with a flange or other suitable fittings that can be connected to the sampling valve. The outlet end should be open. 6 Safety precautions
6.1 Overview
6.1.1 The following safety precautions are commonly applied and have good practice, but they are not all-inclusive. The following matters should also be applied in conjunction with the appropriate national safety regulations or rules recognized by the petroleum industry. Whenever these precautions are implemented, they should not conflict with local or national safety regulations that must be followed.
The nature and known hazards of the sampled materials should be carefully considered because it will affect the details of the safety precautions that need to be followed.
6.1.2 The sampling personnel should be made aware of the potential hazards in the sampling work and be educated on the safety precautions. Instructions for use:
3] Cited from ISO3171:1988 "Automatic pipeline sampling method for petroleum liquids". 5.1
GB/T4756-1998
6.1.3 All safety regulations including entry into hazardous areas should be strictly followed. 6.1.4 During sampling, care should be taken to avoid inhalation of petroleum vapors and wear protective gloves that are insoluble in hydrocarbons. Eye protection or face shields should be worn in places where there is a risk of splashing. When handling sour crude oil, necessary precautions should be added. 6.1.5 When handling leaded fuel, safety regulations should be carefully followed. 6.2 Equipment
6.2.1 Regarding the mechanical properties of the equipment, the receiver or container should be appropriately designed in accordance with relevant national or international standards. Pressure tests and other inspections should be carried out by competent personnel in accordance with local regulations, and the test results should be recorded. Cleaning and leakage inspections should be carried out regularly.
6.2.2 The rope used to lower the sampling device should be an electrical conductor. It should not be made entirely of artificial fibers, and it is best to use natural fibers such as Manila hemp or sisal.
6.2.3 Portable metal sampling instruments for use in flammable atmospheres shall be made of non-sparking materials. 6.2.4 The sampler shall have a holder for carrying the sampling instrument so that at least one hand is free. 6.2.5 Lamps and flashlights used in electrical classification areas shall be of an approved type. 6.2.6 The sampler shall wear appropriate clothing and equipment to protect against all known hazards associated with the material being sampled. 6.2.7 If the Reid vapor pressure (RVP) of the product being sampled is between 100 kPa (1.0 bar) and 180 kPa (1.8 bar), the sample bottle shall be protected in a metal box until the sample is discarded. If it exceeds 180 kPa, only metal samplers that are manufactured to include the pressure involved should be used (see 1.2).
6.2.8 Volatile samples should not be heated in airtight containers. 6.3 Sampling Points
6.3.1 Sampling points should be able to obtain samples in a safe manner. Any potential hazards associated with sampling should be clearly indicated, and it is recommended to install a pressure gauge.
6.3.2 Sampling points and sampling equipment should be regularly maintained and regularly inspected by the competent person, and the inspection results should be recorded. 6.3.3 Safe access to sampling points should be well lit. Access ladders, stairs, platforms and railings should be kept in a structurally safe condition and regularly inspected by the competent person.
6.3.4 Adequate and safe discharge facilities should be installed for discharge and flushing needs. 6.3.5 Any leak or malfunction on the equipment should be reported immediately to the competent person. 6.3.6 When sampling, care should be taken to avoid inhalation of petroleum vapors. 6.3.7 Floating roof tanks should be sampled from the top platform whenever possible because toxic and flammable vapors can accumulate above the top. When it is necessary to descend to the top to take a sample, at least two persons wearing breathing apparatus should be present unless the atmosphere above the top has been tested and found to be safe. The second person or persons should be stationed at the head of the stairs where they can clearly see the sampler on the top. After the sampler has descended to the top to take the sample, he should return to the head of the stairs as soon as possible. Certain conditions that can make the atmosphere above the floating roof hazardous are: a) the product contains hydrogen sulfide and volatile mercaptans; b) the floating roof is not fully buoyant;
c) the floating roof seal fails.
6.4 Static Electricity
To avoid static electricity hazards, the following precautions should be observed when flammable hydrocarbons are stored in tanks at temperatures above their flash point or when flammable nitrogen or oil mist with hydrocarbon vapors has been generated in the tank. 6.4.1 Storage tanks, road tankers, rail tankers, tankers or barges should not be sampled during filling, especially when loading newly refined volatile products, which will increase the flammable vapor-air mixture in the upper space of the tank. 6.4.2 When sampling, in order to prevent sparks, the sampling wire should be firmly grounded during the entire sampling process. The grounding method is either direct grounding or maintaining firm contact with the sampling port. 6.4.3 When taking samples of newly refined volatile products (including kerosene and gas oil) filled at a temperature close to or above its flash point, the conductive sampling device must be introduced into the tank 30 minutes after the transfer or filling is completed. Sampling may be performed within 30 minutes of filling if one of the following conditions exists: a) Floating roof tanks, sampling in slotted metering tubes; b) Solid roof tanks, equipped with grounded floating covers; c) The product contains sufficient antistatic additives to ensure that the total conductivity is greater than 50 pS/m and there is no oil mist or fines formed in the oil-free space (see Note 6).
Note 6: Antistatic additives can increase the conductivity of hydrocarbon liquids to prevent the accumulation of static charge. The total conductivity should be greater than 50 pS/m. At this conductivity, the release time of accumulated charge in the liquid is very short and the charge disappears almost as soon as it is formed. Therefore, as long as there is no oil mist or fines formed in the oil-free space, it is possible to measure and sample without extended time or even during filling, as long as there is no oil mist or fines formed in the oil-free space. Charged droplets can exist in oil mist or fines and will cause a sudden accumulation of static charge, regardless of the presence of antistatic additives in the liquid product. 6.4.4 Sparking shoes shall not be worn in areas where flammable gases may be present. It is recommended that rubber shoes not be worn in dry areas. 6.4.5 Anti-static clothing should be worn and clothing made of synthetic fibers should not be worn. 6.4.6 Sampling should not be carried out during atmospheric electrical disturbances or ice storms. 6.4.7 In order to ground the static charge on the human body, before sampling, the sampler should touch a conductive part on the tank at least 1 meter away from the sampling port.
7 Operation method
7.1 Introduction
In this chapter, the general method is used to sample homogenous oil products, while the additional method in Chapter 8 is used to sample crude oil and non-homogeneous oil products.
Unless otherwise specified, multiple point samples should be collected using the detailed method for special applications. 7.2 Precautions
7.2.1 General precautions
7.2.1.1 The sample should not include materials other than those being sampled. If the sample must be transferred from the sampler to a container, appropriate precautions must be observed to maintain the integrity of the sample. NOTE 7: Transferring samples generally has the following effects: a) loss of light components (affecting density and vapor pressure); and b) changes in relevant properties of the oil and contaminants, such as water and sediment. 7.2.1.2 The sampling personnel should be fully aware of the sampling methods. In order to ensure that the samples are as representative as possible of the material being sampled and suitable for the required tests, the sampling and handling methods must be correctly and clearly defined. When taking samples for certain tests, special care is required and proper sampling methods should be strictly followed to ensure that the test results are meaningful. These additional precautions are not part of this standard and should be listed in the relevant test methods or product specifications. 7.2.1.3 Samples should not be taken from unperforated stationary pipes, guide posts, or risers because the contents of unperforated pipes are generally not representative of the bulk contents at alternate depths in the tank or at relative locations outside the pipe. Stationary pipe, guide post, or riser samples should only be taken from perforated pipes because the oil inside and outside the pipe can flow freely. NOTE 8: A row of holes 25 mm in diameter and 300 mm apart is generally sufficient to allow free flow of oil in and out of the tube. 7.2.1.4 For handling the sample, the sampling apparatus, container and receiver used shall be impermeable and resistant to solvents (see 5.1).
7.2.1.5 Carefully inspect the sampling apparatus, including the closure, to ensure that it is clean and dry. 7.2.1.6 A minimum of 10% oil-free space shall be left in the container for expansion. It is not a good idea to obtain 10% oil-free space by pouring, as this will make the sample unrepresentative, especially when free water or an emulsion layer is present. If the spot sample is taken from the oil tank, some sample must be poured out of the sample container. This operation should be done immediately when the sample container is removed from the oil tank. 7.2.1.7 After filling the sample, immediately close the receiver or container and check it for leaks. 7.2.1.8 When a large volume of sample is required due to volatility or other considerations, it is not necessary to take a large number of small samples. Instead, use appropriate methods (such as circulation, tank side mixer) to completely mix the oil in the tank. Then, according to 4.2 and 8.2.1, take samples at a sufficient number of different liquid levels to determine the uniformity of the oil in the tank through tests. Extend the inlet of the sampling tube to near the bottom of the container, and fill the sample container through the tank side valve, the circulating pump discharge valve or through a siphon. 7.2.2 Samples for special analysis If the sample is used to determine trace substances, such as lead, it may be recommended in the test method to prepare a special sample container. Take the sample directly into the prepared container. The auxiliary equipment and sampling rope used must not contaminate the sample. If the test to be performed on the sample has certain special requirements, such as copper or silver strip corrosion tests, the sample should be placed in a brown glass bottle to protect the sample from light before testing. Sampling by any other method may affect the corrosion test results. If tests of such properties as water separation characteristics, oxidation stability, potential colloids, etc. are required, care should be taken to ensure that the sample container is properly prepared and completely free of contaminants such as flux or other chemicals. 7.2.3 Volatile Materials
7.2.3.1 When sampling volatile crude oils and products, if it is necessary to avoid the loss of light components, such as for density, vapor pressure or distillation determinations, the oil should not be transferred or combined from the original sample container. When transporting and storing samples, the sample container should be inverted to avoid the loss of light components through the closure.
7.2.3.2Depending on the nature and temperature of the liquid, the ambient temperature and the purpose of the sample required, the following precautions must be observed: a) Output the sample through a sample cooler at the sampling point; b) Cool the sample container to the appropriate temperature; c) Keep the sample container cool until it is sealed. If necessary, the sample container can be cooled by immersing it in a cooling medium (such as crushed ice). 7.2.4 Tank side and pipeline sampling
If a tank side or pipeline sampling point is used, the following additional sampling precautions must be taken. a) Before taking a tank side or pipeline sample, the sampling pipeline must be thoroughly flushed to ensure that previous residues in the pipeline are removed. b) During sampling, the sample pipeline outlet should extend near the bottom of the sample container. c) If the material being sampled is volatile, the sample container must be cooled to an appropriate temperature. If necessary, an in-line cooler must be used.
d) If the sampled oil has a high pour point, the sampling pipeline must be insulated or provided with heating facilities to prevent the oil from solidifying.
7.2.5 Labeling and transportation
7.2.5.1. Label the sample container clearly, preferably with a strap label. The label should include the following and use permanent markings. - the place where the sampling was done;
- the date the sampling was done;
the name or other mark of the person taking the sample;
a description of the material being sampled:
- the quantity represented by the sample;
- the can number, the package number (and type), the name of the vessel: the type of sample;
the sampling device used.
it is recommended that detailed records be kept in a work manual for easy reference. 7.2.5.2 If samples are distributed, care must be taken to comply with the relevant regulations. If absorbent packaging material is used, the cork or neck of the bottle should be covered with a paper, plastic or viscose cap to prevent contamination of the sample at the mouth of the bottle and to ensure that the material used will not contaminate the sample. 7.3 Sampling of oil tanks
7.3.1 Fixed oil tanks
7.3.1.1 Vertical round simple oil tanks
7.3.1.1.1 Spot sampling
GB/T47561998
Lower the sampler or bottle and cage until its mouth reaches the required depth, open the stopper by appropriate means, and keep the sampling device at the required liquid level until it is full. When taking a top sample, carefully lower the sampler without a stopper until its neck is just above the liquid surface, then suddenly lower the sampler to 150 mm below the liquid surface and lift it out when bubbles stop bubbling, indicating that the sampler is full. When sampling at different liquid levels, samples should be taken from top to bottom in sequence to avoid disturbing the lower liquid surface. 7.3.1.1.2 Composite Samples
Composite samples are prepared by transferring representative aliquots of the individual samples into composite sample containers. NOTE 9: Evaporation of light components and adhesion of water or sediment to the walls of the initial sampler may affect the properties represented by the sample (see 7.2.3). Composite samples may be prepared for testing unless otherwise specified or agreed to by the interested party. Otherwise, individual spot samples shall be tested and the overall test value calculated in proportion to the individual test results and the quantity represented by each sample. 7.3.1.1.3 Bottom Samples
Lower the bottom sampler and place it upright on the tank bottom. After lifting the sampler, if it is necessary to transfer its contents into a sample container, take care to properly transfer the entire sample, including any water and solids that may have adhered to the inside of the sampler. 7.3.1.1.4 Interface Samples
Lower the sampler with the valve open and allow the liquid to flow through the sampler. When the required level is reached, close the valve. Withdraw the sampler. If a transparent tube is used, the presence of the interface can be confirmed by visual inspection of the tube wall and the position of the interface in the tank can be determined from the value on the dipstick. Check that the valve is properly closed, otherwise resample. NOTE 10 The sample may be retained for testing purposes. 7.3.1.1.5 Tank side sampling
This method is not the best and should only be used when no other method is available. The sampling valve should be mounted on the side of the tank and the sampling tube connected to it should extend at least 150 mm into the tank. This is an exception for floating roof tanks where it is not possible to install a sampling tube. The lower sampling tube should be installed at the bottom liquid level of the outlet pipe (see 7.2.4). Before sampling, the sampling tube should be flushed with the product to be sampled. The sample is then placed in a container or receiver. NOTE: When sampling under pressure, be careful when opening the sampling valve. Do not use a cleaning rod to clear a blocked pipe through an open valve. If the product level in the tank is below the upper sampling tube, the tank is sampled as follows: a) If the product level is near the upper sampling tube, two-thirds of the sample is taken from the middle sampling tube and one-third of the sample is taken from the lower sampling tube.
b) If the product level is near the middle sampling tube, one-half of the sample is taken from the middle sampling tube and one-half of the sample is taken from the lower sampling tube.
c) If the product level is below the middle sampling tube, the entire sample is taken from the lower sampling tube. 7.3.1.1.6 Full-layer sampling
This method is not the best method because it cannot be guaranteed that the sampler is filled at a uniform rate. It also cannot ensure that the free descent or regular lifting of the sampler is effective and that the sampler is not completely filled when it is lifted out of the oil (see 5.2.6). 7.3.1.1.7 Routine sampling
This method is not the best method because it cannot be determined that the sampler is filled at a uniform rate. To obtain routine samples, use a bottle equipped with a weighted sampling cage (Figure 2) and, if necessary, an accessory to limit the filling rate (see Figure 4). The sampling bottle and cage are lowered from the surface of the oil to the bottom of the tank at a uniform rate and then raised to the surface of the oil without stopping at any point. When the sampling bottle is withdrawn from the oil, it should be filled with about 75% of the oil, but not more than 85% (see 5.2.5). 7.3.1.2 Horizontal cylindrical and oval tanks should be sampled as described in 7.3.1.1.1 at the level indicated in Table 1 as spot samples. If it is necessary to combine them into composite samples as described in 7.3.1.1.2, they should be combined in the proportions indicated in Table 1. 586 Full-layer sampling
This method is not the best method because it cannot be guaranteed that the sampler is filled at a uniform rate. It is also not possible to ensure that the free descent or regular lifting of the sampler is effective and that the sampler is not completely filled when it is lifted out of the oil (see 5.2.6). 7.3.1.1.7 Routine sampling
This method is not the best method because it cannot be guaranteed that the sampler is filled at a uniform rate. To obtain routine samples, use a bottle with a weighted sampling cage (Figure 2) and, if necessary, an oil filling rate limiting accessory (see Figure 4). Lower the sampling bottle and cage from the surface of the oil to the bottom of the tank at a uniform rate and lift them out of the oil surface without stopping at any point. When the sampling bottle is withdrawn from the oil, it should be approximately 75% filled with oil, but not more than 85% (see 5.2.5). 7.3.1.2 Horizontal cylindrical and elliptical tanks shall be sampled as spot samples at the liquid level specified in Table 1 as described in 7.3.1.1.1. If it is necessary to combine them into a composite sample as described in 7.3.1.1.2, they shall be combined in the proportions indicated in Table 1.6 Full-layer sampling
This method is not the best method because it cannot be guaranteed that the sampler is filled at a uniform rate. It is also not possible to ensure that the free descent or regular lifting of the sampler is effective and that the sampler is not completely filled when it is lifted out of the oil (see 5.2.6). 7.3.1.1.7 Routine sampling
This method is not the best method because it cannot be guaranteed that the sampler is filled at a uniform rate. To obtain routine samples, use a bottle with a weighted sampling cage (Figure 2) and, if necessary, an oil filling rate limiting accessory (see Figure 4). Lower the sampling bottle and cage from the surface of the oil to the bottom of the tank at a uniform rate and lift them out of the oil surface without stopping at any point. When the sampling bottle is withdrawn from the oil, it should be approximately 75% filled with oil, but not more than 85% (see 5.2.5). 7.3.1.2 Horizontal cylindrical and elliptical tanks shall be sampled as spot samples at the liquid level specified in Table 1 as described in 7.3.1.1.1. If it is necessary to combine them into a composite sample as described in 7.3.1.1.2, they shall be combined in the proportions indicated in Table 1.
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