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GB/T 12228-2006 PDF in English


GB/T 12228-2006 (GB/T12228-2006, GBT 12228-2006, GBT12228-2006)
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GB/T 12228-2006: PDF in English (GBT 12228-2006)

GB/T 12228-2006
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.060.00
J 16
Replacing GB/T 12228-1989
General purpose industrial valves - Specification of
carbon steel forgings
ISSUED ON: DECEMBER 25, 2006
IMPLEMENTED ON: MAY 01, 2007
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Requirements ... 5 
4 Test methods ... 8 
5 Inspection rules ... 9 
6 Ordering requirements ... 10 
7 Marking and quality certificate ... 10 
General purpose industrial valves - Specification of
carbon steel forgings
1 Scope
This Standard specifies the requirements, test methods, inspection rules, order
requirements, markings and quality certificates of compression carbon steel
forgings, such as general purpose industrial valves, flanges, and pipe fittings.
This Standard applies to compression carbon steel forgings, such as general
purpose industrial valves, flanges, and pipe fittings (hereinafter referred to as
forgings). It can be implemented by reference for non-compression forgings.
2 Normative references
The terms in the following documents become the terms of this Standard by
reference to this Standard. For dated references, all subsequent amendments
(not including errata content) or revisions do not apply to this standard. However,
parties to agreements that are based on this Standard are encouraged to study
whether the latest versions of these documents can be used. For undated
references, the latest edition applies to this Standard.
GB 150, Steel pressure vessels
GB/T 228, Metallic Materials - Tensile Testing at Ambient Temperature (GB/T
228-2002, eqv ISO 6892:1998)
GB/T 229, Metallic materials - Charpy pendulum impact test method
GB/T 231.1, Metallic materials - Brinell hardness test - Part 1: Test method
(GB/T 231.1-2002, eqv ISO 6506-1:1999)
GB/T 699, Quality carbon structural steels
GB/T 2975, Steel and steel products - Location and preparation of samples
and test pieces for mechanical testing (GB/T 2975-1998, eqv ISO 377:1997)
GB/T 13927, Industrial Valves - Pressure Testing (GB/T 13927-1992, neq
ISO 5208,1982)
JB 4726, Carbon and Low-alloy Steel Forgings for Pressure Vessels
JB 4730, Nondestructive Testing for Pressure Equipment
3.5.3 The preparation method of the test piece of mechanical properties shall
be in accordance with the provisions of GB/T 2975; the following methods can
be selected:
a) directly on the part;
b) on the extension of the forging;
c) the same blank for manufacturing the cross section.
3.6 Quality requirements
3.6.1 The surface quality of the forgings shall be good and free of harmful
defects.
3.6.2 When the depth of the forging defect reaches the limit size of the forging,
it is a harmful defect and shall be scrapped.
3.6.3 If the defect depth of the forging does not reach the limit size of the forging,
and it can be removed by machining or grinding, it is a non-hazardous defect,
and can be treated as follows:
a) If the folding depth does not exceed 5% of the limit size or 1.5 mm
(whichever is the smaller value), it does not need to be removed. If the
defect needs to be removed, mechanical processing or grinding shall be
used;
b) For defects such as pits, or damage caused by marking, if the depth does
not exceed the stipulation of 3.6.3a), it does not need to be removed;
c) When the defect exceeds 3.6.3a), the defect shall be removed by
machining or grinding, but the limit size of the forging must be guaranteed.
3.6.4 Welding repair
3.6.4.1 Welding repair is allowed for forgings, or as specified in the order
contract.
3.6.4.2 The welding process, post-weld heat treatment, non-destructive
inspection of welding repair and the requirements for welders shall meet the
requirements of GB 150.
3.6.4.3 The welding repair area shall not exceed 10% of the surface area of the
forging; the depth shall not exceed one third of the limit size of the forging or 10
mm (whichever is less). Otherwise, the consent of the buyer shall be obtained.
3.6.4.4 Before the welding repair, all defects must be removed, and magnetic
powder inspection or other effective inspection methods must be carried out as
required.
3.6.4.5 After the welding repair, the welding area shall be polished and flattened,
and inspected and eliminated according to 4.4.
3.6.4.6 All forgings that have undergone the welding repair shall be subjected
to stress relief treatment.
3.6.4.7 The number of welding repairs for the same defect shall not exceed
twice.
3.7 Forging grade
3.7.1 The grade and technical requirements of forgings (including rolled
forgings) shall meet the requirements of JB 4726.
3.7.2 Forgings whose nominal pressure is PN2.5 ~ PN10 are allowed to use
forgings of grade-1.
3.7.3 In addition to the provisions of 3.7.4, forgings whose nominal pressure is
PN16 ~ PN63 shall meet the requirements for forgings of grade-II or above.
3.7.4 Forgings whose nominal pressure is not less than PN100 shall meet the
requirements for forgings of grade-III.
4 Test methods
4.1 Tensile testing
4.1.1 Each batch of heat-treated forgings shall be subjected to a tensile testing.
If the same batch of heat-treated forgings includes more than two rolling heat
numbers, each rolling heat number shall be subjected to a tensile testing.
4.1.2 Under the same heat treatment conditions, if the temperature error is
within ±14°C, and there is a high temperature recording device, the unified
rolling heat number is required to have only one tensile testing.
4.1.3 The tensile testing method shall be carried out in accordance with the
provisions of GB/T 228.
4.1.4 If the forging is too small to make the smallest test piece used for tensile
testing on the forging, or the test piece parallel to the main deformation direction
cannot be cut, and the test piece cannot be forged on the device, 1% of the
batch or 10 pieces (whichever is the minimum) can be taken for the hardness
test.
5.2 If the mechanical testing results do not meet the requirements of Table 4,
the heat treatment shall be performed again in accordance with the provisions
of 3.3, and the preparation of test pieces shall be carried out in accordance with
the provisions of 3.5, and the test shall be carried out in accordance with the
provisions of 5.1. However, the number of reheat treatments shall not exceed
twice.
5.3 The pressure testing shall be carried out after the non-destructive test, and
shall be carried out piece by piece. The forging department shall be responsible
for the quality of the test forgings.
6 Ordering requirements
6.1 The order contract or inquiry sheet shall include the following:
a) Product forging drawings, including requirements for surface roughness,
tolerance, material grade number;
b) Supplier’s forging process and drawing (if required, the buyer’s approval
shall be required);
c) The heat treatment and other requirements can be negotiated by both
parties;
d) Acceptance requirements and contents that need to be supplemented.
6.2 If the buyer finds scrapped products during product analysis or mechanical
processing, it shall notify the forging department within the time that is specified
in the contract; if there is no specification, it shall not exceed 30 days.
6.3 The scrapped forging samples shall be kept for 30 days from the date of
sending the test report. The forging department may request re-examination
during this period.
7 Marking and quality certificate
7.1 After passing the inspection, the forging shall be attached with a conformity
mark, which shall include:
a) Factory name or logo;
b) Material code;
c) Heat treatment code;
d) Date of manufacture;
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.