Some standard content:
ICS47.020.01
Ship Industry Standard of the People's Republic of China
CB/T3790-1997
Technical Conditions for Marine Pipe Processing
Rules for marine pipes processing technology1997-10-17Released
China State Shipbuilding CorporationReleased
1998-06-01Implementation
CB/T3790—1997
Cited standards
Pipe cutting
Pipe fitting assembly
Pipe welding
Pipe bending·
Hydrostatic test
Pipe cleaning
Pipe galvanizing and plastic coating
Pipe marking, stacking and lifting,
CB/T3790-1997
This standard is a revision of the two standards CB/Z335-84 "General Technical Conditions for Marine Pipe Processing" and CB'3093--81 "Technical Requirements for Pipe Bending".
The pipe processing inspection items of this standard refer to the contents of the Japanese JSQS standard, and the contents of the chapter on flange connection refer to the relevant provisions of my country's shipbuilding regulations.
This standard adds the basic requirements for expansion joint connection, the welding-before-bending process, and the relevant provisions for pipe marking, stacking and lifting. From the date of implementation, this standard will replace CB/Z335-84 and CB'3093-81 at the same time. This standard was proposed by the Shipbuilding Technology Sub-Technical Committee of the National Technical Committee for Standardization of Marine Ships. This standard is under the jurisdiction of the 11th Research Institute of China State Shipbuilding Corporation. The drafting unit of this standard: the 11th Research Institute of China State Shipbuilding Corporation. The main drafters of this standard: Li Shaodong, Hua Guangen, Yang Jun. 1 Scope
Ship Industry Standard of the People's Republic of China
Technical Conditions for Ship Pipe Processing
Rules for ship pipes processing technology CB/T3790-1997
Classification number: U06
Replaces CB*/Z335-84
CB3093-81
This standard specifies the materials, cutting, assembly, welding, bending, strength test, cleaning and other aspects of ship pipe parts and their quality acceptance index requirements.
This standard is applicable to the processing of seamless steel pipes, welded steel pipes, galvanized welded steel pipes, stainless steel pipes, bimetallic pipes and non-ferrous metal chip pipes for various types of ships.
2 Referenced StandardswwW.bzxz.Net
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. CB/T3365-91 Pipe No-Residue Cutting ProcessCB3366-91 Steel Pipe Plastic Coating Technical Conditions
CB°/Z343-84
3 Materials
General Process for Hot-Dip Galvanizing
3.1 The mechanical properties and chemical composition of pipe materials shall comply with relevant national standards, industry standards and my country's shipbuilding specifications. 3.2 Various pipes are divided into three grades according to their design pressure and design temperature, see Table 1. For Grade I and Grade II piping systems, they must have a certificate of conformity from the ship inspection department and the furnace number of the manufacturer. Straight-grade piping systems should have a certificate of conformity from the manufacturer. Table 1 Piping system grade
Applicable medium
Other medium
Design pressure
Design temperature
Design pressure
Design temperature
≤150
≤300
Design pressure
Design temperature
When one of the design pressure and design temperature of the piping system reaches the requirements of Grade 1 in the table, it is a Grade 1 piping system; when both the design pressure and design temperature parameters reach the requirements of Grade 1 or Grade 2 in the table, it is a Grade 1 piping system or a Grade 2 piping system. Other media refer to air, water, lubricating oil and hydraulic oil, etc. 2
Approved by China State Shipbuilding Corporation on October 17, 1997 and implemented on June 1, 1998||tt| |CB/T3790-1997
3.3 Seamless steel pipes, stainless steel pipes and bimetallic pipes shall not have defects such as cracks, folds, delamination, scars, rolling folds, hairline marks, etc. on their inner and outer surfaces. If any of the above defects exist, they should be removed, and the wall thickness reduction of the removed parts shall not exceed the negative deviation specified in the relevant standards of our country. 3.4 The inner and outer surfaces of welded steel pipes shall not have defects such as cracks, scars, dislocations, burrs, burns, indentations and deep scratches, but small indentations whose depth does not exceed the deviation range specified in the relevant standards of our country, slight dislocations, roller marks, thin iron oxide scales, and traces of grinding and removal of external burrs are allowed. 3.5 The inner and outer surfaces of copper pipes should be smooth and clean, and should not have cracks, pinholes, ring marks, peeling, Defects such as bubbles, rough drawing, inclusions, spots, delamination and pits. However, slight, localized scratches, spots, pits, fine drawing marks and rolling marks that do not cause the outer diameter and wall thickness of the pipe to exceed the deviation range specified in the relevant standards of our country are allowed to exist. 3.6 When ordering carbon steel pipes, stainless steel pipes, copper pipes and aluminum pipes, annealing requirements should be put forward to the manufacturer. 3.7 Connectors such as flanges, sleeves, threaded joints, reducers, expansion joints and shaped elbows must have a material certificate before they can be used.
3.8 The deviation range of the outer diameter and wall thickness of various pipes shall be inspected and accepted according to the relevant standards of our country or the technical requirements of the order. 4 Pipe cutting
4.1 Before cutting the pipe, the quality of the inner and outer surfaces of the pipe shall be inspected, and it must be It is necessary to check whether the pipe material and specifications meet the requirements of the drawings. 4.2 The pipe cutting should be carried out according to the processing task list and relevant drawings of each batch of pipes. 4.3 Non-ferrous metal pipes, galvanized welded steel pipes and steel pipes with an outer diameter less than or equal to 32mm should be cut mechanically or plasma; for steel pipes with an outer diameter exceeding 32mm, gas cutting is allowed; the cutting method of alloy steel pipes should be determined according to the material composition. 4.4 After the pipe is cut, the incision must be trimmed and smooth, oxidation and burrs must be completely eliminated, and the surface area to be removed should be free of rust and impurities that are not conducive to welding. The length of the pipe end to be cleaned shall not be less than 50mm from the cutting end. 4.5 After the pipe is cut, the verticality of the pipe end face and the outer surface of the pipe shall meet the requirements specified in Table 2. Table 2 Verticality of pipe end face and outer surface of pipe Nominal diameter DN
>100~200
5 Pipe fittings
5.1 Welded steel pipe branches
5.1.1 The types of welded steel pipe branches are generally as shown in Figure 1 a, b, c, d. 2
Verticality
Straight branch
Angle branch
CB/T3790
Inclined branch
dY-type branch
For hydraulic system pipes and pipes with a diameter not greater than 32mm, welded branches are not allowed, and finished tees should be used. 5.1.3 Angle branches and Y-type branches should be used as little as possible, and are not allowed to be used in lubricating oil systems and hydraulic systems. 5.1.4 The branch pipe should be located near the flange of the main pipe to remove the welding slag and burrs on the inner wall. The height of the branch pipe should ensure that the flange connection screws are easy to install. 5.1.5 When the wall thickness of the branch pipe is less than 6mm, no beveling is required. When the wall thickness is equal to or greater than 6mm, and when the diameter of the main pipe is greater than or equal to 2.5 times the diameter of the branch pipe, a beveling is made at the end of the entire branch pipe; when the diameter of the main pipe is less than 2.5 times the diameter of the branch pipe, a beveling can be made at the left and right parts of the branch pipe end face along the axis of the main pipe, as shown in Figure 2, and a beveling gate is opened at position 0. CB/T3790—1997
5.1.6 The branch pipe is not allowed to be inserted into the main pipe. The saddle mouth should be well matched with the main pipe. The welding size requirements are shown in the detailed drawings 1, 1, and Ⅱ in Figure 1. Among them, when single-sided welding is used, l=0~1mm, and when double-sided welding is used, l=1.5~2mm. 5.1.7 The branch hole on the main pipe should be coaxial with the inner hole of the branch pipe, and the coaxiality shall not exceed 1mm. 5.2 Copper pipe welding branch pipe
5.2.1 The types of copper pipe welding branch pipes are generally as shown in Figure 3 A and B. K38
When the inner diameter of the main pipe is larger than the inner diameter of the branch pipe, use type A in Figure 3, and when the inner diameter of the main pipe is equal to the inner diameter of the branch pipe, use type B in Figure 3. The insertion end of type A branch pipe shall not exceed the lowest point of the collar. 5.2.3
The junction of type B branch pipe and main pipe shall intersect.
Tee joints can also be used for copper pipe branches. 5.2.6 The branch hole on the main pipe should be coaxial with the inner hole of the branch pipe, and the coaxiality shall not exceed 1mm. 5.3 Flange connection
The type and applicable scope of steel pipe flange connection shall be in accordance with the provisions of Table 3. Type
CB/T3790-1997
Table 3 Steel pipe flange connection type and applicable scope Figure
e(according to Table
6 requirements)
Other media
Steam2
Fuel oil
Other media
Maximum design pressure
Unlimited13
Maximum design temperature
CB/T37901997
Table 3 (end)
58(mia5)
58(min6
8(min5||tt ||1.58(min6)
58(min5)
1.5(min5)
Fuel oil
Other media
Fuel oil
Other media
Applicable scope
Maximum design pressure
Note: 1) "Unlimited" means the maximum pressure or maximum temperature range allowed by shipbuilding regulations for the use of each system pipeline. Maximum design temperature
2) When the B-type flange is used in the steam system, when the pressure is greater than 1.6MPa or the overflow is greater than 300C, the outer diameter of the pipe shall not be greater than 150mm. 6
CB/T3790-1997
See Table 4 for the connection form and application range of copper pipe flanges. Table 4 Copper pipe flange connection form and application scope Figure
Pipe outward expansion
c (according to the requirements of Table 7)
Application scope
Maximum design pressure
Maximum design temperature
CB/T3790-1997
5.3.3 When welding the flange, the gap between the inner hole of the flange and the outer surface of the pipe should not exceed 2mm at any point, and the total gap between two radially opposite points should not exceed 3mm. For DN300mm pipes, the gap can be appropriately relaxed. 5.3.4 The assembly of pipes and flanges should be positioned according to the weld size requirements of various flanges. For pipes that are welded first and then bent, the position of the flange screw hole and the length of the pipe should be determined according to the requirements of the drawings. 5.3.5 After checking that the flange rotation angle and the flange position on the pipe meet the requirements, spot welding is performed to fix them, and the spot welding length is 10mm. For pipes with DN=15～32mm, two symmetrical spot welding is used; for pipes with DN=40~100mm, three spot welding is used with staggered angle of 120°; for pipes with DN≥125～250mm, four spot welding is used with staggered angle of 90°; for pipes with DN≥300mm, eight spot welding is used with staggered angle of 45°. 5.3.6 After the pipe and flange are spot welded, mutual inspection shall be carried out, and the next process can be entered only after it is deemed qualified. 5.4 Connection of expansion joints
5.4.1 Expansion joints approved by the ship inspection department can be used for pipeline connection of seawater, fresh water, air, lubricating oil, steam and other systems. The working temperature of the medium used is -30～200C; the working pressure for steam system shall not exceed 1.0MPa, and the working pressure for other pipeline systems shall not exceed 1.6MPa.
5.4.2 For pipes with DN≤50mm, nut-type expansion joints can be used, and their structural form is shown in Figure 4. Figure 4
5.4.3 For pipes with DN ≥ 65 mm, gland-type expansion joints can be used, and their structure is shown in Figure 5. Figure 5
5.5 Threaded joint connection
5.5.1 Threaded joints should comply with relevant national standards or industry standards of my country, and various forms of threaded joints should be selected according to the working pressure and working temperature of the pipeline medium.
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