GB/T 20801.4-2006 (GB/T20801.4-2006)

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GB/T 20801.4-2006: PDF in English (GBT 20801.4-2006)

ICS 23.040
J74
National Standard of the People's Republic of China
Pressure Piping Code-Industrial Piping
Part 4. Fabrication and Assembly
ISSUED ON. DECEMBER 30, 2006
IMPLEMENTED ON. JUNE 1, 2007
Issued by General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China
Standardization Administration of the People's Republic of China
Content
Scope .. 1
2 Normative References . 1
3 Terminology and Definitions .. 1
4 General Provisions . 2
5 Inspections and Acceptance of Piping Subassemblies and Supports .. 3
6 Piping Fabrication .. 5
7 Welding . 10
8 Preheating . 20
9 Heat Treatment .. 21
10 Assembly and Erection .. 27
11 Stainless Steel and Nonferrous Metal Pipes .. 34
12 Pipe Cleaning, Blowing and Washing .. 36
Pressure Piping Code-Industrial Piping-Part 4. Fabrication and
Assembly
1 Scope
The other requirements on the fabrication and assembly not included in this part shall
comply with the provisions of the other parts of the Code (GB/T20801-2006), as well as the
applicable national standards and norms.
2 Normative References
The provisions contained in the following documents shall have become the provisions
of this Code when they are quoted hereof. The dated documents so quoted and the
modification lists (excluding the corrections) or revisions made thereafter shall not be
applicable to this Code; however, all parties who have reached agreements based on this Code
are encouraged to study the possibility to implement the latest version of these documents. Of
the undated documents so quoted, the latest version shall be applicable to this Code.
Examination and management rules for boiler and pressure vessel pressure piping
welders
GB/T 17116.1 -1997 Pipe supports and hangers-Part 1. Technical specifications
GB/T 20801.1 -2006 Pressure piping code-Industrial piping-Part 1. General
GB/T 20801.2-2006 Pressure piping code-Industrial piping-Part 2. Material
GB/T 20801. 3 - 2006 Pressure piping code-Industrial piping-Part 3. Design and
calculation
GB/T 20801. 5-2006 Pressure piping code-Industrial piping-Part 5. Inspection and
test
GB/T 20801.6-2006 Pressure piping code-Industrial piping-Part 6. Safeguarding
JB 4708-2005 Welding Procedure Qualification for Pressure Equipment
3 Terminology and Definitions
3.1 Manufacture
The production process of pipe and piping subassembly or piping supports and other
products thereof; Products should meet the requirements of the corresponding product
standards, the relevant specifications and design documents.
3.2 Fabrication
Preparations before pipe installation work, including cutting, processing thread, opening
groove, forming, bending, welding and assembling the parts into subassemblies; The
fabrication can be carried out in the workshop or on site.
3.3 Assembly
Two or more piping subassemblies are to be connected together by way of bolts, welding,
bonding, thread, hard soldering, soft soldering method or by sealing elements in accordance
with the provisions of engineering design.
3.4 Erection
It is to install one piping system completely onto the appointed location and supports
according to the provisions of engineering design, which shall include all the on-site
(including pipe pre-fabrication) assembling, fabrication, inspection and test and so on of the
system as required by the specifications.
3.5 Isometric diagram
It is to draw the pipeline elevation system in single line by axonometric projection
method for each pipeline.
3.6 Hot bending
It is the pipe bending operation when temperature is higher than the metal critical point
ACl.
3. 7 Cold bending
It is the pipe bending operation when temperature is lower than the metal critical point
ACl.
3.8 Pipe-segments to be prefabricated
It is pipe segment determined by the isometric diagram that can be processed before
piping is fabricated.
3.9 Pipe-segments for dimension adjustment
It is pipe segment determined by the isometric diagram that can be processed after
dimensions are measured before piping is erected.
3.10 Tack weld
It is the weld used to maintain all parts of weld assembly in correct positions before the
final weld is completed.
4 General Provisions
4.1 Piping fabrication and installation units should have the quality management system or
quality assurance system in line with the regulatory requirements for pressure pipeline safety
supervision.
4.2 Piping Fabrication and Assembly shall establish and properly keep the necessary
construction records and witness documents. Upon the completion of pressure piping, the
Fabrication and Assembly units shall at least submit to the Owner the following technical
documents and data.
a) Piping as-built drawings (including design modification documents and material
substitution list). The design modifications and material substitution and other
changes should be directly indicated on the as-built drawings.
On the piping isometric diagram it shall indicate the weld position, weld number,
welder code, welding position, reworked weld, non-destructive testing methods and
the weld sampled, the weld for expanded test, and the weld subject to heat treatment
and hardness spot checks, etc.
b) Product certifications, quality certificates or re-inspection and test reports for
pressure piping subassemblies and supports and welding materials.
c) Construction inspection records and inspection and test reports. The formats and
contents of which should be consistent with the provisions of the corresponding
codes for construction and acceptance.
d) Project handover acceptance certificate.
5 Inspections and Acceptance of Piping Subassemblies and Supports
5.1 Acceptance on materials, marking and quality certifications
The marking and quality certifications of piping subassemblies shall, in addition to the
acceptance to be made according to the requirements as set forth in design documents and 9.2
and 9.3 in Part 2 of this Code (GB/T 20801.2-2006), also conform to the following provisions.
a) For the materials subject to low-temperature impact toughness test as specified in the
design documents, the certifications shall contain the results of such low-temperature
impact toughness test.
b) For the stainless steel pipes and fittings subject to intergranular corrosion test as
specified in the design documents, the certifications shall contain the results of such
intergranular corrosion test.
c) When the performance data contained in the quality certifications do not meet the
requirements of product standards or design documents, or there are objections on
performance data, it should carry out the necessary additional tests.
5.2 Visual examination
The material grade, size and appearance quality of piping subassemblies and supports
shall be subject to visual inspection and spot check on geometrical dimensions according to
the corresponding standards, those unqualified should not be put into use.
5.3 Material quality inspection
5.3.1 The piping subassemblies made of alloy steel, nickel-containing low temperature steel,
molybdenum-containing austenitic stainless steel and nickel-based alloys, titanium and
titanium alloy materials shall be retested on the main alloying elements by spectral analysis or
other methods for 5% of each batch (the same furnace batch and specifications, the same
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