GB 50128-2014 English PDF (GB50128-2014)

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GB 50128-2014: Code for construction and acceptance of vertical cylindrical steel welded storage tanks
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 hois...