GB/T 19326-2022 English PDF (GB/T19326-2022)

GB/T 19326-2022: Forged branch outlet fittings
Delivery: 9 seconds. Download (& Email) true-PDF + Invoice.
Get Quotation: Click GB/T 19326-2022 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 19326-2022
Preview True-PDF (Reload/Scroll-down if blank)

GB/T 19326-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.040.60
CCS J 15
Replacing GB/T 19326-2012
Forged branch outlet fittings
锻制支管座
ISSUED ON: JULY 11, 2022
IMPLEMENTED ON: FEBRUARY 01, 2023
Issued by: State Administration for Market Regulation;
National Standardization Administration.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Types and codes ... 6
5 Pressure class ... 6
6 Pipe connection size ... 9
7 Special branch outlet fitting ... 9
8 Order content ... 9
9 Shape, size, tolerance ... 10
10 Materials ... 26
11 Design, manufacture, installation ... 26
12 Heat treatment ... 28
13 Inspection and testing ... 28
14 Marking ... 29
15 Surface protection and packaging ... 30
16 Product quality certificate ... 31
Appendix A (Normative) Design verification test ... 32
Appendix B (Informative) Installation guide ... 36
References ... 39
Forged branch outlet fittings
1 Scope
This document specifies the types and codes, pressure class, pipe connection sizes,
special branch outlet fittings, ordering content, shape, size and tolerance, material,
design and manufacturing, heat treatment, inspection and testing, marking, surface
protection and packaging, product quality certification requirements of forged branch
outlet fittings; provides installation guidelines.
This document applies to branch outlet fittings forged with steel materials in pipeline
systems.
Note: The branch outlet fittings in this document refer to branch outlet fittings with different
diameters, that is, branch outlet fittings with trunk pipes larger than branch pipes.
2 Normative references
The contents of the following documents constitute essential clauses of this document
through normative references in the text. Among them, for referenced documents with
dates, only the versions corresponding to the dates apply to this document; for
referenced documents without dates, the latest versions (including all amendments)
apply to this document.
GB/T 9124 (all parts) Steel pipe flanges
GB/T 12459 Steel buttwelding pipe fittings - Types and parameter
GB/T 12716 Pipe threads with the thread angle of 60 degrees where pressure-tight
joints are made on threads
GB/T 14383 Forged fittings, socket-welding and threaded
GB/T 18253-2018 Steel and steel products - Types of inspection documents
GB/T 20801.3 Pressure piping code - Industrial piping - Part 3: Design and
calculation
GB/T 28708 Specification for size selection of seamless and welded steel pipe used
in piping engineering
NB/T 47013.3 Nondestructive testing of pressure equipment - Part 3: Ultrasonic
testing
fittings and elbow branch outlet fittings and other branch outlet fittings that exceed the
nominal size and wall thickness range of the trunk pipe listed in Table 2. When using
relevant calculations, analysis or verification tests, the manufacturer shall keep these
documents and provide them to the purchaser for inspection when necessary.
The socket welding, threaded and butt welding 90° branch outlet fittings (including
extended branch outlet fittings, flange branch outlet fittings, thin-walled branch outlet
fittings) with the outer diameter size of the body listed in Tables 4 ~ 14 and Tables 18
~ 20 have passed the limit reinforcement calculation of opening reinforcement,
according to the corresponding maximum wall thickness of the trunk pipe.
11.3 The allowable pressure rating of the branch outlet fitting manufactured according
to this document can be calculated, based on the seamless straight pipe (trunk pipe
welded to the branch outlet fitting) of the same specification, material and wall
thickness.
11.4 When the wall thickness class of the branch pipe connected by the branch outlet
fitting is different from the wall thickness class of the branch pipe listed in Table 2, the
following provisions shall apply:
- When the wall thickness of the branch pipe is thicker, the corresponding branch
outlet fitting size shall be selected according to the wall thickness of the trunk pipe;
the flow aperture (d) shall be determined according to the inner diameter of the
branch pipe; in this case, the other dimensions of the butt-welded branch outlet
fitting may not be changed; the end outer diameter (D2) of the socket-welded and
threaded branch outlet fitting shall not be less than the sum of the outer diameter
of the branch pipe and twice the wall thickness of the branch pipe plus 2 mm. If
the end outer diameter (D2) is larger than the outer diameter of the body (D1), the
end outer diameter (D2) plus 2 mm shall be used as the size of the outer diameter
(D1) of the body;
- When the wall thickness of the branch pipe is thinner, the corresponding branch
outlet fitting size shall be selected according to the wall thickness of the trunk pipe;
the flow aperture (d) shall be determined according to the inner diameter of the
branch pipe. In this case, other parameters may change, so one of the methods
specified in 11.2 shall be used to determine whether the branch outlet fitting design
meets the reinforcement requirements.
11.5 The branch outlet fitting can be made by cutting from forgings or bars. When
forging is used, the material shall be forged as close to the specified shape and size as
possible.
11.6 When forging with steel ingots, the head and tail of the ingot shall be fully cut off,
to ensure that defects such as shrinkage, looseness, cracks, excessive segregation are
eliminated.
11.7 When forging with steel ingots, billets or continuous casting billets, the forging
ratio of the main cross-section of the forging shall be greater than or equal to 3; when
forging with bars, the forging ratio of the main cross-section of the forging shall be
greater than or equal to 1.6.
11.8 For the installation guide of the branch outlet fitting, see Appendix B.
12 Heat treatment
12.1 Except as specified in 12.2, the heat treatment of the branch outlet fitting shall
comply with the provisions of the corresponding parts of GB/T 14383.
12.2 When the manufacturing conditions meet the following requirements, heat
treatment is not required.
a) Branch outlet fittings with a material category of carbon steel (excluding carbon
steel branch outlet fittings in low-temperature steel) less than or equal to DN100
and a final forging temperature of not less than 700 °C.
b) Branch outlet fittings made directly from bar cutting, meanwhile the raw materials
have been heat treated or the carbon steel materials are in hot-rolled state when
leaving the factory.
c) For forgings with material classes of SF304, SF304L, SF316, SF316L less than
or equal to DN100, when the final forging temperature is not less than 1040 °C,
they can be quickly cooled in water after final forging to replace solution
treatment.
13 Inspection and testing
13.1 Except for the provisions of 13.2 ~ 13.5, the inspection and testing of branch outlet
fittings shall comply with the provisions of the corresponding parts of GB/T 14383.
13.2 After negotiation between the supplier and the buyer, branch outlet fittings formed
by die forging with material category of carbon steel and less than or equal to DN100
can be accepted, only on the basis of hardness test; in this case, the hardness value shall
be 110 HBW ~ 160 HBW.
13.3 For branch outlet fittings formed by free forging process, ultrasonic testing shall
be carried out piece by piece according to NB/T 47013.3 after heat treatment; level I is
qualified.
13.4 For branch outlet fittings formed by free forging process with material category of
carbon steel, low temperature steel and alloy steel, magnetic particle testing shall be
carried out piece by piece according to NB/T 47013.4; level I is qualified.
pipe × thread size code of branch pipe is DN600×NPT1⅟2, is marked as:
Manufacturer name or trademark AF11 Product number or raw material melting furnace
number XS×3000 DN600×NPT1⅟2 THD-ELB-OL
Example 3: The flat-end extended branch outlet fitting, which has a material class LF485K2,
impact test temperature of -50 °C, wall thickness class of trunk pipe × branch pipe of Sch160
×Sch160, nominal size of trunk pipe × branch pipe of DN40×DN25, is marked as:
Manufacturer name or trademark LF485K2 S050 Product number or raw material smelting
furnace number Sch160×Sch160 DN40×DN25 PE-NIP-OL
Example 4: The flange branch outlet fitting, which has a material class SF2507, trunk pipe wall
thickness class × flange pressure class of STD×CLASS300, trunk pipe nominal size × flange
nominal size of DN80×DN50, flange sealing surface code RF, flange standard number GB/T
9124.2, is marked as:
Manufacturer name or trademark SF2507 Product number or raw material smelting furnace
number STD×CLASS300 DN80×DN50 RF-GB/T9124.2 FLG-OL
Example 5: The butt-welded thin-walled branch outlet fitting, which has a material class
SF304/304L, wall thickness class of trunk pipe × branch pipe Sch10S×Sch10S, nominal size of
trunk pipe × branch pipe DN50×DN15, is marked as:
Manufacturer name or trademark SF304/304L Product number or raw material smelting furnace
number Sch10S×Sch10S DN50×DN15 BW-PIP-OL
15 Surface protection and packaging
15.1 The surface of the branch outlet fitting shall be clean, free of rust, burrs and
attachments. The branch outlet fitting with forged surface should be sandblasted or shot
blasted. The non-cutting surface of the stainless steel branch outlet fitting shall be
pickled and passivated; the branch outlet fittings of other materials can be protected by
surface blackening, anti-rust paint or weldable paint.
15.2 The branch outlet fitting can be galvanized according to the purchaser's
requirements. For branch outlet fittings that require hot-dip galvanizing, the socket or
threaded part of the branch outlet fitting shall be processed after hot-dip galvanizing.
15.3 Branch outlet fittings shall be packaged separately according to different material
classes; pay attention to moisture-proof. A packing list shall be attached to the package
box.
Appendix A
(Normative)
Design verification test
A.1 General
When the manufacturer uses verification test to evaluate the design of the branch outlet
fitting, it shall be in accordance with the provisions of this Appendix.
The verification test shall be based on the calculated test pressure of the sample and its
connected pipe section. The test adopts the burst test method.
A.2 Test assembly
A.2.1 Sample
The sample shall be taken from the finished branch outlet fitting with similar structure,
same manufacturing method, same material property classification [see A.8d)]; the
material class and size shall be checked. All requirements shall comply with the
provisions of this document.
Note 1: Different varieties of 90° branch outlet fittings are of similar structure; the test of one
90° branch outlet fitting can represent other 90° branch outlet fittings with different branch
connection methods, including extended branch outlet fittings and flange branch outlet fittings.
Different types of 45° branch outlet fittings and elbow branch outlet fittings are of similar
structure; the test of one 45° branch outlet fitting can represent other 45° branch outlet fittings
with different branch connection methods, including elbow branch outlet fittings.
Note 2: Branch outlet fittings made by machining from forgings and branch outlet fittings made
by direct machining from bars belong to different manufacturing methods.
A.2.2 Pipe sections
The pipe sections of the trunk pipe and branch pipes connected to the sample by welding
shall be equivalent to the material of the sample and shall meet the requirements of the
corresponding steel pipe standards. The calculated burst pressure of the pipe section
shall not be lower than the test pressure specified in A.6. The wall thickness of the pipe
section of the trunk pipe and branch pipe shall be consistent with the corresponding
wall thickness class listed in Table 2; it shall also meet all requirements of the steel pipe
specification.
The branch opening size of the trunk pipe shall be equal to the flow aperture (d). The
length of the trunk pipe on both sides of the weld shall be at least twice the outer
diameter of the trunk pipe, or a suitable length that can ensure that the verification test
results will not be affected after welding. The extension length of the branch pipe is at
A.7.1 Applying test pressure
The test assembly shall be pressurized uniformly at an appropriate rate using a pump
with appropriate pressurization capacity. First, the trapped air in the assembly shall be
removed; then uniform pressure shall be applied until the yield point of the material (at
this time, any unnecessary measuring instruments on the assembly can be removed);
the pressure shall be increased uniformly again, until rupture or the required test
pressure is reached/exceeded and maintained for at least 3 minutes. The pressure of the
test assembly may be increased to compensate for the reduction in test pressure caused
by the yielding of the test assembly.
A.7.2 Recording pressure-time readings
The test pressure and time readings shall be recorded regularly. Calibrated electronic
devices should be used to complete the recording.
A.7.3 Test results
If any part of the test assembly (e.g., sample, trunk pipe, branch pipe, or weld, etc.) fails
during the test, the test shall be terminated. If there is any leakage in the test assembly
before or during the calculated test pressure, the test is unsuccessful. The test is
qualified only when the test assembly reaches at least the calculated verification test
pressure and maintains it for at least 3 minutes continuously without showing sealing
failure or cracks, or when the test assembly ruptures after exceeding the calculated
verification test pressure.
A.8 Applicability of test results
It is not necessary to test all branch outlet fittings of different varieties, specifications,
pressure class, mate...