Some standard content:
National Standard of the People's Republic of China
Urea synthesis tower
Technical conditions
Specifications for urea reactor1 Subject content and scope of application
This standard specifies the urea synthesis tower in the urea plant Manufacturing inspection and acceptance regulations. UDC 66.06: 661 | Hereinafter referred to as stainless steel) lined urea synthesis tower.
In addition to complying with the provisions of JB741 "Technical Conditions for Steel Welded Pressure Vessels", JB754 "Technical Conditions for Multi-layer Pressure Vessels", and JB2532 "Technical Conditions for Hot Jacketed Pressure Vessels", the manufacturing of urea synthesis towers should also comply with this Standards and drawing requirements. 2 Reference standards
GB983 stainless steel welding rod
GB1220
stainless steel rod
GB2270
GB2485
GB2489
GB3323|| tt||GB4226
GB4233
GB, 4237
stainless steel seamless steel pipe
grinding wheel
sheet grinding wheel
Radiography and Quality Grading Stainless Steel Cold-Worked Steel Bars
Stainless Steel Rods and Wires for Inert Gas Welding Stainless Steel Hot Rolled Steel Plate
ZBG93001
ZBG93002
ZBG93003
ZBG93004
ZBG93005
ZBG93008
ZBG93009
JG69
JB741
JB754
JB1151
Go to Super Sample preparation for intergranular corrosion tendency test of low carbon austenitic stainless steel Urea high pressure equipment manufacturing and inspection method
Urea high pressure equipment manufacturing and inspection method Ultra low carbon austenitic stainless steel intergranular corrosion tendency test Urea high pressure equipment manufacturing and inspection Methods
Selective corrosion inspection and metallographic inspection of ultra-low carbon austenitic stainless steel Urea high-pressure equipment manufacturing and inspection methods
Urea high-pressure equipment manufacturing and inspection methods
, stainless steel strip automatic stack Welding layer ultrasonic inspection of urea synthesis tower ammonia leakage test method
Urea high-pressure equipment surfacing process assessment and welder skills assessment Welding process assessment and welder skills assessment of urea high-pressure equipment lining plates and internal parts Lining asbestos board|| tt||Technical conditions for steel welded pressure vessels
Technical conditions for multi-layer pressure vessels
Ultrasonic flaw detection of high-pressure seamless steel pipes
JB1614
JB2532
JB2536
3Materials
Mechanical performance inspection method of welded joints of boiler pressure components Technical conditions of heat-jacketed pressure vessels
Painting, packaging and transportation of pressure vessels
3.1 Urea synthesis tower Materials of pressure components and materials in contact with corrosive media must have quality certificates. 3.2 Requirements for stainless steel (including molten metal). The Ministry of Chemical Industry of the People's Republic of China approved the implementation on 1989-03-01 on August 16 | It should be made of 00Cr17Ni14Mo2 modified or 00Ct25Ni22Mo2 stainless steel. In addition to complying with the requirements of GB4237, GB2270, GB1220, GB4226, GB983, GB4233 and other material standards, the stainless steel used shall also comply with the provisions of paragraphs 3.2.1 to 3.2.4 of this standard. 3.2.1 Chemical composition
3.2.1.1 The chemical composition of stainless steel plates, pipes, bars and forgings should comply with the requirements in Table 1. Table 1
%
Material
Material
00Cr17Ni14Mo2
Improved type
00Cr25Ni22Mo2 type
C||tt| |Si
<0.030
<1.00
<0.020
<0.40
Mn
<2.00
P| |tt||化
<0.035
1.50~2.00
<0.020
学
s
<0.030||tt| |0.015
Into
Min
Ni
>13.00
Cr
>17.00
21,50~22.5024 .50~25.50
3.2.1.2 The chemical composition of the deposited metal of welding materials such as welding rods, welding wires, welding ribbons, and fluxes should comply with the requirements in Table 2. Table 2
Welding materials
(high manganese type)
00Cr17Ni14Mo2
Improved type
00Cr25Ni22Mo2 type
c
<0.045
<0.045
Cr
17.00~
19.50
24.00~
26.00
3.2.2 Gold Phase structure and ferrite content.
Ni
14.00~
18.00
19.00~
23.00
化
Mo
2.20 ~
3.00
1.90~
2.40
学
N-containing steel
<0.20
≤0.20|| tt||N
成
Mn
4.00~
7.00
3.00~
-5.50
points| |tt||Si
<1.00
<0.50
Mo
>2.20
1.90~
2.30
p
<0.030
N
N-containing steel
<0.20
0.10~
0.14
%|| tt||S
<0.020
<0.020
<0.030
Stainless steel (including deposited metal) shall be single-phase austenite after final heat treatment or after welding The body structure should not have a continuous network of carbides or g-phase. The ferrite content shall not exceed 0.6%. 3.2.3 Intergranular corrosion tendency test.
The specimens for intergranular corrosion tendency test of stainless steel (including deposited metal) shall comply with the provisions of ZBG93001. The intergranular corrosion tendency test method shall comply with the provisions of ZBG93002, and the average corrosion rate CR of the five cycles shall comply with the following provisions. a.00Cr17Ni14Mo2 improved stainless steel: CR<3.3μm/48hb.00Cr25Ni22Mo2 stainless steel: CR<1.5μm/48h. 3.2.4 Selective corrosion inspection and metallographic inspection. All lining plates and their welded joint samples that have been tested for intergranular corrosion tendency must undergo selective corrosion inspection and metallographic inspection; for internal parts and other stainless steel (including deposited metal) samples that are in contact with corrosive media, if When the corrosion rates in the fourth and fifth cycles of the intergranular corrosion tendency test exceed 50% of the corrosion rates in the third and fourth cycles respectively, these samples must undergo selective corrosion inspection and metallographic inspection. The inspection method should comply with the regulations of ZBG93003. The inspection results shall comply with the following provisions. 3.2.4.1 On the inspection section of the specimen, the selective corrosion depth 8 facing the corrosive medium shall comply with the following regulations: GB9842—88
. The base material and deposited metal are both 00Cr17Ni14Mo2 modified stainless steel (as shown in Figure 1a): the base material (plate, pipe, bar, forging) and its welding heat affected zone (HAZ)) The selective corrosion depth 8 shall not be greater than 70 μm in the direction perpendicular to the rolling or forging direction, and shall not be greater than 200 m in the direction parallel to the rolling or forging direction. The selective corrosion depth of molten metal should not be greater than 200 μm in any direction. b. The base material is 00Cr17Ni14Mo2 improved stainless steel, and the molten metal is 00Cr25Ni22Mo2 stainless steel (if 1b is left). The selective corrosion depth of the base metal and its welding heat-affected zone shall comply with the provisions of item a. The selective corrosion depth of the molten metal shall not exceed 100 μm in any direction.
00Cr17Ni14Mo2 melting number metal 3200μm sample inspection section
Rolling or forging direction
Base metal 200mwww.bzxz.net
Material 870m
HAZ870μm
Figure 1
3.2.4.2 Metallographic structure shall comply with the provisions of Section 3.2.2. 3.3 Re-inspection of stainless steel
The stainless steel materials used should be re-inspected according to the following provisions and meet the requirements of Article 3.2. 3.3.1 The chemical composition of raw materials such as plates, pipes, bars and forgings shall be retested according to the batch number.
a.
b., determine the ferrite content piece by piece.
00Cr25Ni22M02 melting number Golden Eagle<100m
Sample inspection sugar surface
Base material 0<200um
1.A.2.
870μm|| tt | |Experiment.
When the total number exceeds 5 pieces, take 1 sample for every 5 pieces, and take 1 sample for the remaining less than 5 pieces; when the total number is 5 pieces, take 2 samples,
When the total number is less than 5 pieces, take 1 sample. When taking more than two samples, they must not be taken from the same raw material. The preparation of sample should comply with the provisions of ZBG93001. Selective corrosion inspection and metallographic inspection should be carried out in accordance with the provisions of Section 3.2.4. d.
The size, shape (flatness according to GB4237I board assembly requirements) and surface quality of the lining sheets should be checked one by one. e.
f． Stainless steel high-pressure seamless pipes with an outer diameter greater than 20mm should undergo ultrasonic flaw detection one by one and comply with the regulations of JB1151. 3.3.2 Welding materials
The chemical composition, ferrite content, intergranular corrosion tendency test and selection of welding materials such as electrodes, welding wires, welding ribbons and fluxes should be re-inspected according to the furnace (batch) number. Corrosion inspection and metallographic inspection. 3.4 Marking of stainless steel
3.4.1 Confirmation marks should be made on stainless steel materials that have passed the re-inspection. This mark should be transplanted to a visible part of the part during the manufacturing process. 3.4.2 Waterproof ink or paint that does not contain metallic pigments, sulfides, or chloride ions containing no more than 25 Ppm should be used to write marks on stainless steel; a round-headed dotted line with a tip radius of no less than 0.15mm can also be used for marking. GB9842-88
3.5 Asbestos board for manhole sealing gasket, in addition to complying with the requirements of JG69, its chloride ion content should not exceed 100Ppm. 4 Hot and cold processing forming
4.1 Preparation of welding grooves of stainless steel parts
Machining methods should be used to prepare welding grooves. If thermal cutting (such as plasma cutting) is used to prepare welding grooves, metal that affects corrosion resistance must be removed by grinding. The groove surface must be inspected by ferrite content measurement and coloring flaw detection. 4.2 Grinding of stainless steel parts
4.2.1 Rubber or nylon-mixed alumina grinding wheels should be used to grind stainless steel parts. The quality of the grinding wheels should comply with the regulations of GB2485 and GB2489. Grinding wheels that have been used to grind carbon steel must not be used to grind stainless steel. 4.2.2 No tempering color is allowed in the polished areas of the lining or its welds. 4.2.8 The lining surface in contact with corrosive media should be polished after grinding. 4.3 Protection of the lining surface during the manufacturing process
4.3.1 During the manufacturing process, the lining surface should be prevented from being damaged by molds, tool fixtures, arcs, splashes, etc. Damage that affects the corrosion resistance must be repaired, and the grinding depth should be Not exceeding the requirements of Table 23 in GB.4237. 4.3.2 During the manufacturing process, oil, chlorine-containing materials and ferritic steel should be prevented from contaminating the lining surface. 4.4 Spherical head
4.4.1 The spherical head shall comply with the provisions of JB741 Article 6 (1), (2) and (4). Check the flap curvature of the split stamping spherical head on a sample that is at D and not less than the arc length of the spherical flap. The chord length of any part of 4.4.2
is not less than
3
The gap should be no more than 2.5mm.
Note: D. is the nominal inner diameter of the container (the same below). 4.4.3. The offset amount b of the butt weld of the integrally stamped spherical head should not be greater than 2mm (Figure 2). The misalignment b of the flap butt weld of the split stamping spherical head should not be greater than 10% of the plate thickness and not greater than 3mm; however, when the plate thickness exceeds 80mm, the misalignment b of the butt weld should not be greater than 5mm. Figure 2 | Marginal quantity provisions. Dm | 1.25%D, the lower deviation should not be greater than 0.625%Dg, and the transition should be smooth. Shape
Figure 4
4.4.6 Before lining or surfacing stainless steel on the head, the inner surface should be machined or polished smooth, and defects that affect the quality of the lining or surfacing layer are not allowed.
4.5 barrel sections
4.5.1 The misalignment of the longitudinal welds of the inner barrel of the multi-layer shell or the barrel sections of the single-layer shell should not be greater than 1.5mm (Figure 5), and the edges and corners of the longitudinal welds E should be no larger than 2mm (Figure 6).
1/6D
Picture 5
and not less than 300ml
Picture 6
1/6Dg, and not less than 300mm
4.5 .2 Before thermal sleeve lining and loose lining, the oxide scale, oil dirt and other dirt on the inner wall of the low alloy steel cylinder that is fitted with it should be removed, and the misaligned edges, edges and corners of the welds and other protrusions and depressions must be ground. Smooth and does not allow defects that affect the quality of the lining. 4.5.3 The difference e between the maximum inner diameter and the minimum inner diameter of the same section of the cylinder section should not be greater than 0.5%Dg and not greater than 6mm. 4.6 Assembly
4.6.1 The offset amount of the bad weld should meet the following requirements: when the thickness of the lining plate is less than or equal to 8mm, the offset amount should not be greater than 2.5mm. When the thickness of the lining plate is greater than 8mm, The amount of misalignment should not be greater than 3mm. 4.6.2 Lining
4.6.2.1 The lining should be close to the inner wall of the cylinder and head. You can tap the lining with a wooden hammer or a 100-150g stainless steel hammer to check the tightness. The area of ??any single non-fitting area should not be larger than 250cm2, and its length should not be larger than 300mm. The total non-fitting area should not be larger than 10% of the total area of ??the lining. %. The maximum local radial gap where any end does not fit should not be greater than 1mm. 4.6.2.2 The distance between two adjacent splicing welds of the lining plate, the distance between the lining longitudinal welds of adjacent barrel sections, and the distance between the end points of the head lining splicing welds and the adjacent barrel section lining longitudinal welds should not be less than 100mm. . 14.6.2.3 The edge of the weld connecting the tray bracket and the lining should be staggered from the edge of the longitudinal seam of the lining, and the staggering distance should not be less than the thickness of the lining plate. GB 984288
The distance between the tray bracket and the edge of the lining ring seam should not be less than 50mm. 4.6.3 The straightness tolerance of the tower shall not be greater than 6mm for every 6m of length, and the cumulative deviation of the total length shall not be greater than 0.05% of the simplified length. 4.6.4 The distance deviation from the half surface of the lower head base to the container baseline should not be greater than 6mm (Figure 7). Container baselines should be permanently marked.
Datum line
Alignment plane
1 side of base
Figure 7
4.7 Trays and tray brackets
4.7.1 The local flatness of the tower plate should not be greater than 2mm within the length of 300mm; the bending within the entire plate surface should comply with the requirements in Table 3. Table 3
Tray length
<.1000
1000~1500
-1500
Bent
not greater than||tt| | 3.0 | | tt | | 3.5 | | tt | | 4.0 | The chord length tolerance is no more than 2mm. 4.7.3 The maximum deviation in the elevation of tray brackets on the same layer is 3mm. 4.7.4. The tolerance of the spacing between two adjacent tray trays shall not be greater than 3mm. The tolerance of the distance between any two tray brackets shall not be greater than 10mm. 4.7.5 The segmented trays should be pre-assembled and the installation dimensions should be checked before delivery. 5 Welding
mm
5.1 The welding of pressure parts, the welding of pressure parts and non-pressure parts, and the welding of stainless steel (including positioning welding) must be undertaken by qualified welders. Welders must strictly abide by the welding procedure regulations. 5.2 The welding procedure specifications must be prepared according to the technical requirements of the drawings and the welding procedures qualified by the welding unit. GB9842-88 | Conduct welding process qualification before welding the urea synthesis tower. 5.4 The welding procedure assessment and welder skill assessment of stainless steel should comply with the regulations of ZBG93009 and ZBG93008. 5.5 Unless otherwise specified in the drawings, all stainless steel butt welds and fillet welds in contact with corrosive media (such as the fillet welds of lining plates and tower brackets, etc.) should be fully penetrated structures.
5.6 The end face of stainless steel pipes exposed to corrosive media must be covered with welding materials that meet the requirements of Article 3.2. 5.7 The stainless steel strip electrode surfacing shall have no less than 2 layers (including 1 transition layer and no less than 1 corrosion-resistant layer), and the stainless steel manual surfacing shall have no less than 3 layers (including 1 transition layer and no less than 1 corrosion-resistant layer). less than 2 layers). The total thickness of the surfacing corrosion-resistant layer (measured from the lowest point on its surface): the lining part shall not be less than 3mm; the sealing surface part shall not be less than 6mm after processing. 5.8 Linear weld beads should be used for welding stainless steel, and the interlayer temperature should not be greater than 150°C; the weld surface in contact with corrosive media should be welded last. The arc shall not be started or closed on the surface of the non-welded area of ??the lining. 5.9 The surfacing welding of stainless steel with spherical head should also meet the following requirements: the welding beads of large-area manual surfacing should be arranged in strips or concentric circles, and the arc closing points of the same welding layer can be in a diagonal line or on the same bus line. , the overlap width of adjacent welding beads is generally one-half of the welding bead width. The weld beads with pole surfacing should be arranged in concentric circles. The first and last overlapping points of each concentric circle weld bead should be on the same bus line. The corrosion-resistant layer weld bead should be parallel to the transition layer weld bead, and the corrosion-resistant layer weld bead should be parallel to the transition layer weld bead. The overlap weld line should be staggered with the overlap weld line of the covered layer. 5.10 Use a 10x magnifying glass to inspect the inner and outer surfaces of the stainless steel lining weld and the surface of the surfacing layer. The appearance quality should meet the following requirements: There must be no defects such as cracks, pores, arc craters, slag stains, lack of fusion or undercuts on the surface of the surfacing layer, welds and heat-affected zones; b. For pores or slag stains with a diameter less than 0.5mm, and a depth less than 0.5mm Defects such as undercuts are allowed to be removed by grinding and the transition is smooth; the thickness after grinding should not be less than the minimum allowable thickness of the lining base material and surfacing layer; when the size of the defect exceeds the above regulations, it should be removed and repaired after welding. c. The fillet weld should have a smooth transition to the geometry of the base metal. 5.11 The repair of stainless steel butt welds, fillet welds and surfacing layers should comply with the following regulations: grinding methods should be used to remove impermissible defects, and repair welding should be carried out according to qualified repair welding processes,
b .The number of repairs on the same part of the weld and surfacing layer should not exceed two times. If the above regulations are exceeded, approval must be obtained from the technical director of the manufacturing unit. After repair, the repair location, number of times, and non-destructive testing results will be recorded in the quality certificate. 5.12 Welding records must be kept when welding stainless steel (including return repair welding). The welder should promptly mark the welder mark at the specified location near the weld. On stainless steel surfaces in contact with corrosive media, only written marks are allowed, and welder stamps are not allowed. 6 Heat treatment
6.1 Any stainless steel internal parts or lining parts that have one of the following conditions should be heat treated. 6.1.1 For stainless steel cladding, stress relief heat treatment should generally be carried out after the transition layer is cladded and before the corrosion-resistant layer is cladded. 6.1.2 Stainless steel parts with a cold forming deformation rate exceeding 20% ??should be subjected to solution heat treatment to improve corrosion resistance. 6.1.3 After hot forming, stainless steel parts should be subjected to solid solution heat treatment to improve corrosion resistance. 6.2 The stress relief heat treatment temperature should comply with the requirements in Table 4. Table 4
Stainless steel surfacing transition layer material
00Cr17Ni14Mo2 improved type
00Cr25Ni22Mo2 type
Stress relief heat treatment temperature, ℃
510±10||tt ||560±10
Stainless steel parts shall not be subjected to local heat treatment or more than two overall solution heat treatments. 6.3
GB9842-88
6.4 Before stainless steel parts are heated, grease, paint and other contaminants must be removed. All tool fixtures that need to be in contact with stainless steel heating elements must be made of stainless steel. Tool fixtures that are in direct contact with heated stainless steel parts need to be preheated. 6.5 Solid solution heat treatment requires a heat treatment test plate and should be heat treated in the same furnace. 6.6 After heat treatment, stainless steel parts must be pickled. 7 Test pieces
7.1·The number of lining stainless steel welded test plates for each tower should meet the following requirements. 8. Every 5 lining cylinder sections welded should be equipped with at least one longitudinal weld test plate, and the remaining less than 5 lining cylinder sections should be equipped with at least one longitudinal weld test plate, b. Each spherical head lining must be equipped with at least one spliced ??weld test plate, c. For any lining parts that need to be heat treated to meet corrosion resistance requirements, each heat batch number must be equipped with at least one heat treatment test plate. 7.2 The preparation of lining welding test plates, in addition to complying with the provisions of Article 29 (1), (2) and (3) of JB741, should also meet the requirements of Article 7.3 of this standard and ZBG93001 sample preparation.
7.3 Inspection of lining welding test plates.
7.3.1 The appearance quality of the weld shall comply with the provisions of Article 5.10. 7.3.2 The determination of the ferrite content of the weld shall comply with the provisions of Article 8.4 and shall be carried out together with the weldment. 7.3.3. Weld coloring and flaw detection shall comply with the provisions of Article 8.5 and shall be carried out together with the weldment. 7.3.4. Welds should be 100% X-ray inspected, and radiographic quality and weld quality should comply with the requirements of Level AB and Level I in GB3323 respectively.
7.3.5 The chemical composition of the weld deposited metal shall comply with the provisions of item 3.2.1.2. 7.3.6 The intergranular corrosion tendency test of welded joints shall comply with the provisions of Section 3.2.3. 7.3.7 The selective corrosion inspection and metallographic inspection of the weld deposited metal, base metal and heat-affected zone shall comply with the provisions of Section 3.2.4. 7.3.8 The welded joint of the lining plate of each tower must undergo at least one tensile test and comply with the requirements of JB1614. The tensile test results should not be lower than the standard value of the base material. 7.4. The solution heat treatment test plate shall be subjected to surface quality inspection, ferrite content determination, intergranular magic corrosion tendency test, selective corrosion inspection, metallographic structure inspection and tensile test. The results shall comply with 3.2 and 7.3.8. Provisions. 8 Non-destructive inspection
8.1 Non-destructive inspection must be undertaken by qualified non-destructive inspection personnel. 8.2 Non-destructive inspection process procedures should be formulated according to product technical requirements and operated in accordance with the procedures. 8.3 The appearance quality of stainless steel welds, heat-affected zones and surfacing layers shall comply with the provisions of Article 5.10. 8.4 The ferrite content of the stainless steel weld and surfacing layer surface should be measured, and the ferrite content at any measuring point shall not exceed 0.6%. 8.5 The surface of stainless steel welds and surfacing layers shall be subjected to coloring and flaw detection in accordance with Appendix 6 of JB741 and the following provisions. The results shall comply with the provisions of paragraphs a and b in Article 5.10.
8: The surface of internal parts and lining welds (including fillet welds on the lining, etc.) must undergo 100% coloring flaw detectionb. The lining surfacing layer must undergo at least two coloring inspections. The first time is carried out when the transition layer surfacing is started. The surface area of ??the transition layer inspected should not be less than 30% of the total surfacing area; the third time is after the corrosion-resistant layer surfacing is started. The surface of the corrosion-resistant layer must undergo 100% coloring and flaw detection. 8.6 The surface of the stainless steel strip cladding layer and the processed manual cladding layer must be subjected to ultrasonic flaw detection and thickness measurement of the cladding layer in accordance with the provisions of ZBG93004.
The thickness of the surfacing layer shall comply with the provisions of Article 5.7 or the drawing. 8.7 All lining welds welded outside the tower should be subject to 100% X-ray inspection. The radiographic quality and weld quality should comply with the requirements of Level AB and Level I in GB3323 respectively.
8.8 When non-destructive inspection of stainless steel butt welds, fillet welds and surfacing layers reveals impermissible defects, the defects should be removed and repaired in accordance with the provisions of Article 5.11, and the repaired parts should be re-inspected by non-destructive inspection. Until qualified. 9 Hydraulic pressure test and ammonia leakage test
GB 9842--88
9.1 After the urea synthesis tower is manufactured, a hydraulic pressure test and an ammonia leakage test should be carried out. 9.2 In addition to complying with the provisions of Chapter 7 of JB·741, the hydraulic test should also comply with the following provisions. a.The nitrogen ion content of water used for hydraulic pressure testing should not be greater than 25ppm; b. The temperature of the water during the hydrostatic test should be 5°C higher than the brittle transition temperature of the urea synthesis tower shell material, and not lower than 15°C. When the temperature of the tower body is approximately the same as that of the water, pressurization begins to reach the test pressure; c. After the hydraulic pressure test, 100% coloring and flaw detection should be carried out on the surface of the lining weld. 9.3 The ammonia leakage test shall comply with the following requirements. 8. After the hydraulic pressure test, an ammonia leakage test must be conducted on the lining layer; b. The leak detection system must be unobstructed;
The ammonia leakage test on the lining layer should comply with the regulations of ZBG93005. c.
10 Surface treatment of stainless steel
After the urea synthesis tower passes the ammonia leakage test, the stainless steel surface should be pickled and passivated. 10.1
Note: Whether passivation treatment is performed at the container manufacturer shall be determined by agreement between the user and the container manufacturer. 10.2 After pickling and passivation, it must be rinsed immediately with water containing less than 25 ppm chloride ions until the pH test paper shows neutral. 10.3 Treatment after pickling and passivation.
a: Remove accumulated water in the tower and keep the inner surface of the tower dry and clean; b. Replace the asbestos gasket used for manhole seals during hydrostatic testing; seal all openings (including leak detection pipes). c.
Paint, packaging, transportation, marking and factory technical documents 11
The paint, packaging, transportation and marking of the urea synthesis tower should comply with the regulations of JB2536. 11.1
For urea synthesis towers transported by sea, the tower should be filled with 0.03MPa nitrogen, and seawater must be prevented from contaminating the stainless steel. 11.2 The nameplate of the urea synthesis tower should include the following content: name of the manufacturing unit;
a.
product name
b.
c.
d.| |tt||e.
Product number of the manufacturing unit;
Manufacturing date;
Design pressure:
f.
Hydraulic test pressure;
g.
h.
Design temperature;
Container weight.
11.3． The factory technical documents of the urea synthesis tower should at least include the following contents. 11.3.1
11.3.2
Factory certificate.
Installation and operating instructions:
a. Urea synthesis tower characteristics (including design pressure, test pressure, design temperature, working medium); special requirements for operation,
b.#
c.
special requirements such as no welding and installation illustrate.
11.3.3
As-built drawing.
11.3.4
Quality certificate:
a.
The chemical composition, mechanical properties and re-inspection report of the main component materials (including welding materials); Lining and internal parts materials should also have reports for ferrite determination, intergranular corrosion tendency test, selective corrosion inspection and metallographic inspection, as well as surface quality inspection of the lining plate.
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