GB 50128-2014 PDF in English
GB 50128-2014 (GB50128-2014) PDF English
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Name of Chinese Standard | Status |
| GB 50128-2014 | English | 285 |
Add to Cart
|
0-9 seconds. Auto-delivery.
|
Code for construction and acceptance of vertical cylindrical steel welded storage tanks
| Valid |
| GB 50128-2005 | English | RFQ |
ASK
|
3 days
|
Code for construction and acceptance of vertical cylindrical steel welded storage tanks
| Obsolete |
Standards related to (historical): GB 50128-2014
PDF Preview
GB 50128-2014: PDF in English GB 50128-2014
UDC GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
G 51
P GB 50128-2014
Code for Construction of Vertical Cylindrical Steel
Welded Storage Tanks
ISSUED ON: APRIL 15, 2014
IMPLEMENTED ON: JANUARY 1, 2015
Issued by: Ministry of Housing and Urban-Rural Development of the
People's Republic of China;
General Administration of Quality Supervision, Inspection
and Quarantine of the People's Republic of China.
Table of Contents
Foreword ... 5
1 General Provisions ... 7
2 Terms ... 7
3 Material Acceptance ... 8
4 Prefabrication ... 9
4.1 General Requirement ... 9
4.2 Shell Plate Prefabrication ... 11
4.3 Bottom Plate Prefabrication ... 13
4.4 Floating Roof Prefabrication ... 15
4.5 Top Plate Prefabrication of Fixed Roof ... 16
4.6 Accessories Prefabrication ... 17
5 Assembly ... 17
5.1 General Requirement ... 17
5.2 Foundation Inspection ... 18
5.3 Tank Bottom Assembly ... 19
5.4 Shell Plate Assembly ... 20
5.5 Fixed Roof Assembly ... 24
5.6 Floating Roof Assembly ... 24
5.7 Accessories Installation ... 25
6 Welding ... 25
6.1 General Requirement ... 25
6.2 Welding Procedure Qualification and Welding Procedure Specification ... 26
6.3 Welding Material ... 26
6.4 Welding Construction ... 27
6.5 Welding Sequence ... 29
6.6 Repair and Rework ... 30
7 Inspection and Acceptance ... 32
7.1 Welding Seam Appearance Inspection ... 32
7.2 Welding Seam NDT Test and Leakage Test ... 33
7.3 Tank Geometry and Dimension Inspection ... 36
7.4 Hydro-test ... 37
7.5 Project Completion ... 39
Appendix A Fillet Welding Seam Test Specimen Preparation and Inspection for
T-shape Joint ... 41
Appendix B Storage Tank Foundation Settlement Observation Method ... 43
Appendix C Acceptance Forms ... 45
Explanation of Wording in This Code ... 57
List of Quoted Standards ... 58
1 General Provisions
1.0.1 This code is formulated to standardize the construction of vertical cylindrical welded
steel tanks, guarantee the engineering quality and make it advanced in technology,
cost-effective, safe and applicable.
1.0.2 This code is applicable to the construction of vertical cylindrical welded steel tank
body at and close to normal pressure for storing petroleum and petrochemical products and
other similar liquids, including accessories welded with the tank, but not applicable to the
construction of buried tank, tank holding extremely and highly hazardous medium and
artificial refrigerant fluid tank.
1.0.3 Tanks shall be constructed according to design documents. In case design documents
are required to be revised, written consent of the original design organization shall be first
obtained.
1.0.4 Prefabrication, installation and inspection of tanks shall be performed with qualified
measuring tools with the same accuracy grade.
1.0.5 The construction of vertical cylindrical welded steel tanks shall not only meet those
specified in this code, but also those in the current relevant standards of the nation.
2 Terms
2.0.1 Annular/sketch bottom plates
The tank bottom plates at the outermost side of the lower part of the shell plate,
including annular edge plates and non-annular edge plates.
2.0.2 Fixed roofs
The tank roofs with peripheral parts connected, in fixed method, with the tank shell top,
mainly including self-supporting cone roof, supporting cone roof and self-supporting dome
roof etc.
2.0.3 Floating roofs
Roofs which lifts with the liquid level, including external floating roof and internal
floating roof, and mainly being single-deck floating roof, double-deck floating roof, open-top
bulk-headed floating roof and floating roof on floats etc.
2.0.4 Wind girder
Member arranged onto the shell to make it stronger to resist wind.
2.0.5 Auto vent
The venting device which opens/closes automatically when the floating roof rises or
restores to be in bracing state.
2.0.6 Floating roof drains
Equipment which drains the rainwater on external floating roof out of the tank under
normal conditions.
3.0.6 Material re-inspection shall meet the requirements of the design documents.
3.0.7 In case of any doubt about material quality, re-inspection shall be performed by the
party purchasing such material.
4 Prefabrication
4.1 General Requirement
4.1.1 Sample plate for tank prefabrication and installation inspection shall meet the
following requirements:
1 the chord length of arc-shaped sample plate shall not be less than 1.5m in case the
curvature radius is less than or equal to 12.5m or 2m in case the curvature radius is greater
than 12.5m.
2 the length of linear sample plate shall not be less than 1m.
3 for the arc-shaped sample plate for measuring weld angularity, its chord length shall
not be less than 1m.
4.1.2 The method to prefabricate the tank shall not damage the base material or reduce the
performance of base material.
4.1.3 Cutting of tank members and processing of weld groove shall meet the following
requirements:
1 carbon steel and low alloy steel members should be machined or processed by way
of automatic and semi-automatic flame cutting; stainless steel members shall be machined or
processed by way of plasma cutting;
2 if the operating temperature is less than the following temperature listed, steels shall
not be cut:
1) -16℃ for common carbon steels;
2) -12℃ for low alloy steels.
4.1.4 Weld groove shall be processed to be flat and smooth, free from slag inclusion,
delamination or crack and other defects; hardened surface layer generated on weld groove due
to flame and plasma cutting shall be removed.
4.1.5 As for shell plate of which the minimum yield strength specified in the standard is
greater than 390MPa, if its weld groove is processed by way of flame cutting, groove surface
shall be subjected to magnetic particle or penetrant testing after the removal of hardened layer,
and testing methods and criterion of acceptability shall meet the requirements of 7.2.9 of this
code.
4.1.6 If no required in design documents, groove type and dimension of welded joints shall
be selected according to the current national standards Recommended Joint Preparation for
Gas Welding, Manual Metal Arc Welding ,Gas-shield Arc Welding and Beam Welding (GB/T
985.1) and Recommended Joint Preparation for Submerged Arc Welding (GB/T 985.2); types
of butt joints for electro-gas welding and submerged arc welding respectively for longitudinal
welding seam and circumferential welding seam of the tank shall also meet the following
requirements:
Figure 4.1.6-2 -- Butt Joint Formed Through Submerged Arc Welding of Circumferential Welding Seam
4.1.7 Common carbon steel members shall not be subjected to cold sizing and cold bending
in case the operating ambient temperature is less than -16℃, nor the low alloy steel members
in case the operating ambient temperature is less than -12℃.
4.1.8 Deformation, damage and corrosion shall be avoided in the preservation, transport and
on-site stacking of tank members.
4.1.9 Prefabrication of stainless steel tank shall also meet the following requirements:
1 stainless steel materials shall not contact with carbon steel and materials for storing
peroxides;
2 stainless steel plate shall not be stamped with embossed marks or portrayed with
labels, but be marked with colourant easy to scrub;
3 stainless steel plate and members should be hoisted with lifting belt, and transport
mould shall be provided with protection measures;
4 stainless steel plate and members shall not be hammered directly with hammer, and
the surface shall be free from scratch, bruise, arc scratch and corrosion, and shall be smooth;
5 stainless steel members shall not be formed by way of fire bending;
6 dedicated grinding disk or belt shall be used to polish the stainless steel materials.
4.1.10 All prefabricated members of the tank shall be with serial number once finished, and
be marked clearly with paint or other methods.
4.2 Shell Plate Prefabrication
4.2.1 Cutting plan shall be drawn before prefabrication of tank shell plate and meet the
following requirements:
1 longitudinal welding seams of shell plates at various rings should be staggered ring
by ring along the same direction, and the clearance between longitudinal welding seams of
shell plates at adjacent rings should be 1/3 of the plate length and shall not be less than
300mm.
2 the distance between the longitudinal welding seam of the shell plate at bottom ring
and the butt welding seam of the sketch bottom plate shall not be less than 300mm.
3 the distance from shell opening to longitudinal and circumferential welding seams
center of the tank shell, as well as to the fillet welding seam at the uttermost end of the tank
shell shall meet the following requirements:
1) the distance from nozzle or reinforcement plate outer edge to longitudinal and
circumferential welding seams of the tank shell shall be greater than 8 times the size of the
relatively large weld leg and no less than 250mm in case the shell thickness is greater than
12mm and the nozzle as well as shell plate won't be subjected to stress relief heat treatment
after welding.
2) the distance shall not be less than 150mm from nozzle or reinforcement plate outer
edge to longitudinal welding seam of the tank shell or not less than 2.5 times the tank shell
thickness and 75mm from nozzle or reinforcement plate outer edge to circumferential welding
seam of the tank shell in case tank shells varying in thickness and nozzles are subjected to
post weld heat treatment or the tank shell thicker than 12mm and the nozzle won't be
4.6 Accessories Prefabrication
4.6.1 After being formed by machining, wind girder, stiffening ring, wrapped angle steel,
tensile ring, compressive ring and other arc-shaped members shall be inspected with
arc-shaped sample plate regarding the corresponding radian and the corresponding clearance
shall not be greater than 2mm; their buckling deformation shall be inspected onto the platform
while the deformation amount shall not exceed 0.1% of the member length and shall not be
greater than 6mm.
4.6.2 Members formed by fire bending shall be free from over-burning.
4.6.3 Adjustment amount should be reserved in the prefabrication of floating roof support.
4.6.4 Prefabrication of reinforcement plate for shell opening shall meet the following
requirements:
1 The material of reinforcement plate shall be the same as that of shell plate at
opening.
2 Cutting surface of the reinforcement plate shall be flat and smooth while edges and
corners shall be rounded; its curvature shall be consistent with that of the shell plate at this
position while the permissible deviation shall meet those specified in 4.2.3 of this code.
3 Butt welding seams for spliced reinforcement plate shall be full penetration welding
seams.
4 The reinforcement plate shall be with signal hole. The reinforcement plate
manufactured with a complete steel plate shall be with one signal hole; The reinforcement
plate spliced shall be with one signal hole at each splicing segment. The signal hole should be
M6 ~ M10 and at the bolt hole onto the horizontal centre line.
4.6.5 Prefabrication of structural members shall meet the requirements of design documents.
5 Assembly
5.1 General Requirement
5.1.1 Prior to assembly of tank, groove of the member and rust, moisture as well as dirt at
the overlapping position shall be cleaned up.
5.1.2 Base metal shall not be damaged in the dismantlement of clamping tools assembled.
Craters on the steel plate surface shall be polished until to be smooth; if damaged, base metal
shall be repaired according to the requirements of 6.6 of this code.
5.1.3 Assembly of stainless steel tank shall meet the following requirements:
1 Tank shell, tank bottom and accessories shall not be with embossed marks;
2 Stainless steel materials should be adopted for assembling clamping tools, and
carbon steel clamping tools shall not contact and be welded with stainless steel tank; if
required to be contacted and welded, clamping tools shall be welded with stainless steel
isolation plate;
3 Arc scratch shall be avoided in assembly welding.
5.1.4 Safety measures for assembling technology shall be taken in assembling the tank to
has been welded.
5.6.6 Before assembly of double-deck floating roof, the welding seam covered by ring plate,
partition, truss and reinforcement plate shall be carried out firstly and inspected by vacuum
tank and upon it is qualified, the assembly of double-deck floating roof shall be carried out.
The weld pass shall be subjected to the top plate and accessories installation upon being
qualified.
5.6.7 Assembly of fabricated internal floating roof shall be carried out in accordance with
the design requirements.
5.7 Accessories Installation
5.7.1 Nozzle of tank shall meet the following requirements:
1 The position deviation of nozzle center shall not be greater than 10mm and the
allowable deviation of connection pipe extension length shall be ±5mm.
2 The curvature of opening reinforcement plate shall be consistent with that of tank.
3 The sealing face of nozzle flange shall be free from overlap and scratch. The flange
sealing surface shall be perpendicular with connection shaft unless otherwise specified in the
design documents and the flange face shall be perpendicular or horizontal and declined by 1%
of flange outer diameter or less and shall not be greater than 3mm; the flange bolt hole shall
be installed at mid-span.
5.7.2 Verticality and linearity of the dipping tube and guide tube shall not be greater than
0.1 % of tube height and shall not be greater than 10mm.
5.7.3 In the water filling test of storage tank, the floating roof support height shall be
adjusted according to the actual measurement size.
5.7.4 After rotary joint hardwired floating roof drains system has been pre-casted, the
dynamic test shall be carried out and the test height shall subject to the highest level of the
storage tank in the water filling test.
5.7.5 Sealing device shall be protected during transportation and assembly to prevent the
damage to the rubber products; during the assembly, attention shall be paid to fire protection.
5.7.6 The paraffin cutter shall be tightly close to shell plate and partial maximum clearance
shall not exceed 5mm.
5.7.7 Horizontal projection of rolling ladder central line shall be superposed with track
center line and the deviation shall not be greater than 10mm.
5.7.8 Installation of latticed shell shall meet requirements of design documents.
6 Welding
6.1 General Requirement
6.1.1 The welder for storage tank welding must be assessed according to TSG Z6002
Assessment Rules for Special Equipment Welding Operators and upon being qualified in
the Nation.
6.5 Welding Sequence
6.5.1 The welding of tank bottom shall use the welding procedure and the welding sequence
which may result minimum shrinkage deformation. The welding sequence of tank bottom
should meet the following requirements:
1 In case of welding of bottom sketch plates , shorter welding seams shall be welded
firstly followed by longer ones; the first pass should be welded with the method of back-step
welding or skip welding.
2 The welding of annular bottom plates shall meet the following requirements:
1) Welding shall be applied firstly to welding seams at least 300mm near the
outside edge, after completion of the fillet welding seam of tank bottom and
wall and before the application of welding of shrinkage joints between the edge
plate and the bottom sketch plate, the welding of butt welding seam of
remaining edge plates and bottom sketch plates shall be completed;
2) Welding of the first layer of butt welding seam for annular edge plates should
be made in the way that the welders are evenly distributed to weld it
symmetrically;
3) Welding of the first layer of shrinkage joints between edge plates and bottom
sketch plates shall be made with the method of back-step or skip welding.
3 The tank bottoms with non-annular edge plates should remain no shrinkage joint.
4 The welding of fillet welding seam connecting tank bottom and shell shall be made
after completion of longitudinal seam welding on bottom ring shell and it shall be welded by
several pairs of evenly distributed welders, section by section from inside and outside of tank
along same direction. The fillet welding seam inside the tank shall be welded firstly followed
by the ones outside the tank. The pass of first layer shall be welded with the method of
back-step or skip welding.
6.5.2 The welding sequence of shell should meet the following requirements:
1 Longitudinal welding seams shall be welded firstly followed by circumferential ones.
On completion of the welding of longitudinal welding seams for shell of two adjoining rings,
the circumferential welding seams between them shall be welded; in case the unsymmetrical
grooves are adopted, the side with large groove shall be welded firstly followed by that with
small groove.
2 When gas shielded welding is used for longitudinal welding seams, the welding
should be applied upward. When submerged automatic arc welding is used for circumferential
welding seams, the welding machines should be evenly distributed to apply welding along
same direction; when shielded metal arc welding is used, the welders should be evenly
distributed to apply welding along same direction.
6.5.3 The welding sequence of fixed-roof top plates should meet the following
requirements:
1 The inside welding seams should be welded firstly followed by outside ones. For
radial long welds, the method of symmetric welding of every other weld should be used and it
nominal thickness of steel plates deducting the negative deviation.
2 In case the defect depth or polishing depth exceeds 1mm, it shall be subjected to
repair welding and polished to be smooth.
6.6.2 Repair of welding seam surface defects shall meet the following requirements:
1 In case the welding seam surface defect exceeds those specified in 7.1.2 of this code,
it shall be polished or shall be subjected to repair welding;
2 The welding seam surface defect shall be removed with angle grinder; in case the
welding seam surface is lower than base metal after removal of defect, it shall be subjected to
welding repair;
3 The removal depth of undercut and toe crack on both sides of welding seam shall not
be greater than 0.5mm, if fails to meet the requirements, shall be subjected to welding repair;
4 The undercut of longitudinal welding for shell steel plates with the minimum
standard yield strength greater than 390MPa or low-alloy steel bottom ring shell with the
thickness greater than 25mm shall be repaired and polished to smooth transition with base
metal.
6.6.3 Rework of internal defect of welding seam shall meet the following requirements:
1 Applicable welding method shall be selected, and rework technique shall be
established according to causes of defects.
2 For unacceptable defect inside the welding seam, the buried depth of defect shall be
detected and the removal surface of defect shall be determined before welding repair, the
removal length shall not be less than 50mm and the removal depth should not be greater than
2/3 of the plate thickness; if carbon arc air gouging is adopted, the defect shall be grinded and
grooved after removal.
3 The welding seam after rework shall be subjected to non-destructive testing in
accordance with the former method specified and shall reach the acceptable quality level.
4 The position, time and testing result of repair welding shall be recorded.
6.6.4 The welding of shell steel plates with the minimum standard yield strength of greater
than 390MPa shall be subjected to rework and shall also meet the following requirements:
1 The penetration testing shall be conducted after defect removal and the repair
welding may be conducted after confirmation of no defect. The welding seam shall be
polished to be smooth after repairing and shall be subjected to penetration testing or magnetic
particle testing.
2 During welding repair, a pass of raised temper bead (Figure 6.6.4) shall be added on
the repairing weld bead, which shall be adjusted again to obtain smooth transition with former
weld bead after welding.
3 The testing position for T-shape welding seam of shell shall include 300mm of
longitudinal and circumferential welding seams.
4 The butt welding seam of shell plates where assembly parts of flush-type cleaning
hole are located, and adjacent shell plates shall be subjected to 100% radiographic testing.
5 The non-destructive testing position of above-mentioned welding seams shall be
determined by quality inspector on site.
6 In case the radiographic testing or ultrasonic testing is unqualified, the distance
between the defect and negative plate end or ultrasonic testing end is less than 75mm, the
supplementary testing shall be conducted by extending 300mm at this end; in case the test
result of extending parts remains unqualified, the extended inspection shall be continued.
7 In case the plate thickness is greater than 12mm, the ultrasonic time of flight
diffraction technique may be adopted, and the testing position and proportion shall meet the
above-mentioned requirements in this article.
7.2.5 The inspection of inside fillet welding seam for T-shape joint of bottom ring shell and
bottom shall meet the following requirements:
1 In case the thickness of sketch bottom plates is greater than or equal to 8mm and the
thickness of bottom ring shell plate is greater than or equal to 16mm or that of the shell plates
and bottom plates of any thickness with the minimum standard yield strength specified in the
standard greater than 390MPa, after welding of the inside and outside fillet welding seams,
the inside fillet welding seam shall be subjected to magnetic particle or penetration testing;
after hydro-test of the storage tank, re-testing shall be conducted with the same method.
2 In case the steel plates with minimum standard yield strength greater than 390MPa
are adopted for bottom ring shell and bottom plates, the inside fillet welding seam shall be
subjected to penetration testing after the root weld pass is welded.
7.2.6 The inspection of floating roof shall meet the following requirements:
1 In case the single side continuous welding seams are adopted for floating roof bottom
plate and single-deck plate, the leakage test shall be conducted with vacuum tank, the
negative pressure of test shall not be less than 53kPa and held for at least 5s, and no leakage is
regarded as qualified.
2 In case the two-side continuous welding seams are adopted for floating roof bottom
plate, the continuous welding seam of lower part shall be welded after the welding seams of
upper part are welded and pass inspection according to the requirements of Clause l in this
article; after all welding seams are welded, the inspection may be conducted with kerosene
leakage test method, and no leakage is regarded as qualified.
3 The welding seam of buoyancy chamber ring plate and shifting board shall be
subjected to leakage test with kerosene leakage test method. The welding seam of buoyancy
chamber top plate shall be subjected to leakage test with vacuum tank method or by blowing
in compressed air with the pressure of 785Pa (80mm of water column), the pressure
stabilization time shall not be less than 5min, and no leakage is regarded as qualified.
4 All buoyancy chambers of single-deck floating roof and buoyancy chambers with
sealing structure of double-deck floating roof shall be subjected to leakage test by blowing in
compressed air with the pressure of 785Pa (80mm of water column), the pressure stabilization
time shall not be less than 5min, and no leakage is regarded as qualified.
5 In case the vacuum tank cannot be adopted for leakage test due to structural
meet those specified in 5.4.2 of this code;
4 Allowable deviation of internal surface radius of bottom ring shell shall be measured
at 1m of the bottom ring shell and shall meet those specified in 5.4.2 of this code;
5 Radial distance between external surface of bottom ring shell and outer edge of
bottom stretch plate shall not be less than 50mm and should not be greater than 100mm.
7.3.2 After welding of the tank bottom, depth of partial deformation of unevenness shall not
be greater than 2% of the length of deformation and shall not be greater than 50mm, or 40mm
for the single side tilting tank bottom.
7.3.3 Partial deformation of unevenness for the floating roof shall meet the following
requirements:
1 Partial deformation of unevenness for buoyancy chamber roof shall be measured
with straight sample plate and shall not be greater than 15mm;
2 Partial deformation of unevenness for single-deck plate shall not obviously influence
appearance and roof drains;
3 The inner and outer edge ring plate of floating roof shall meet those specified in 5.6.4
of this code.
7.3.4 Allowable deviation for clearance between floating roof outer edge ring plate and
bottom ring shell at installation site shall be ±15mm; in the whole process of up-and-down of
floating roof in hydro-test, allowable deviation of floating roof at any other heights shall be
±50mm.
7.3.5 Geometric dimension of internal floating roof after assembling and welding shall meet
the following requirements:
1 Allowable deviation for radius of internal floating roof outer edge ring plate shall be
±10mm;
2 For outer edge ring plate of internal floating roof, the verticality deviation after
welding shall be ±3mm, and the clearance of inner arc measured with arc-shaped sample plate
shall not be greater than 8mm;
3 Allowable deviation for clearance between internal floating roof outer edge ring plate
and bottom ring shell shall be ±10mm.
7.3.6 Geometric dimension of fixed roof after welding shall meet the following
requirements:
1 The fixed roof shall be in aesthetic shape; its partial deformation of unevenness shall
be inspected with sample plate and the clearance shall not be greater than 15mm;
2 Verticality of the support column shall not be larger than 1% and shall not be greater
than 10mm.
7.3.7 Geometric dimension of single-layer roof with spherical latticed shell after assembling
and welding shall meet the requirements of the design document and under the action of
design load of external pressure, the allowable deflection of latticed shell is 0.25% of the
inner diameter of oil tank.
7.4 Hydro-test
7.4.1 Once built, the storage tank shall be subjected to hydro-test, in which the following
negative pressure, no abnormal deformation of tank roof is regarded as qualified. After the
test, the interior of storage tank shall be communicated with atmosphere immediately unti......
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
|