The ASME B16.9 standard is a crucial reference for the piping industry. It provides detailed specifications for factory-made, wrought butt-weld fittings, which are essential for connecting pipes in various industrial applications. This ensures smooth flow and structural integrity in systems that transport liquids, gases, or other materials. This guide will cover critical aspects of ASME B16.9, including its scope, fitting types, dimensional tolerances, material requirements, and best practices for selection and installation. Whether you’re an experienced engineer or just getting started, this overview will give you the confidence to master the complexities of butt-weld fittings.
Scope of ASME B16.9
This Standard covers overall dimensions,tolerances, ratings,testing,and markings for factory-made wrought buttwelding fittings in sizes NPS 1/2 through NPS 48 (DN 15 through DN 1200).
| Types | Size |
| 45-deg /90-deg Long Radius Elbows / 3D Elbows / Straight Tees / Straight Crosses / Reducing Outlet Tees / Reducing Outlet Crosses / Caps | 1/2 – 48 |
| Long Radius Reducing Elbows / Long Radius Returns / Short Radius Elbows / Short Radius 180-deg Returns / Lap Joint Stub Ends / Concentric Reducers / Eccentric Reducers | 1/2 – 24 |
Presssure Ratings
Class followed by a dimensionless number is the designation for pressure-temperature ratings.Standard- ized designations for flanges per ASME B16.5 referenced in this Standard are Classes 150, 300, 600, 900, 1500,and 2500.
SIZE
NPS is followed by a dimensionless number, which is an indication of the nominal fitting size. NPS is related to the reference nominal diameter D N used in international standards. In general, the relationship is as follows:
Material
Wrought fittings covered by this Standard shal l be in accordance with ASTM A234 , ASTM A403 , ASTM A420, ASTM A81 5 , ASTM B361 , ASTM B363 , ASTM B366, or the corresponding specificationlisted in ASME BPVC, Section I I . The term “wrought” denotes fittings made of pipe, tubing, plate, or forgings. For purposes of determining proof testing requirements of section 9, the materials are grouped by simi lar properties as shown in Table 5-1.
Fittings made from block forgings may only be supplied subject to agreement between the manufacturer and purchaser. Such fittings need not meet the requirements of section 7.
| Material | Standards |
| Carbon and low-alloy steels | ASTM A234/A234M and ASTM A420/A420M |
| Austenitic and duplex stainless steels | ASTM A403/A403M and ASTM A815/A815M |
| Nickel alloys | ASTM B366/B366M |
| Aluminum alloys | ASTM B361 |
| Titanium alloys | ASTM B363 |
MARKING
Standard Marking
Each fitting shal l be permanently marked to show the following:
(a) manufacturer’s name or trademark
(b) material identification , either the ASTM or ASME grade designation
(c) schedule number1 or nominal wall thickness in mm
(d) size — the nominal pipe size (NPS) identification number re lated to the end connections shal l be used
(e) compliance — see para . 4.4 for standard and special fitting marking
A manufacturer may supplement these mandatory markings with others, includ ing a DN size designation ,but confusion with the required marking shal l be avoided .
Exceptions
Where the size of the fitting does not permit complete marking , the identification marks may be omitted in reverse of the order presented in para . 4.1 .
Depth of Stamping
Where steel stamps are used , care shall be taken so that the marking is not deep enough or sharp enough to cause cracks or to reduce the wall thickness of the fitting below the minimum allowed .
Compliance
Standard Fittings. That the fitting was manufactured in conformance with th is Standard , including all dimensional requirements, is certified by a prefix “WP” in the material grade des ignation marking.
Special Fittings. That the fitting was manufactured in conformance wi th this Standard, except that dimensional requirements are as agreed between the purchaser and the manufacturer, is certified by a supplementary suffix to the material grade designation marking as follows :
(a) “S58” of ASTM A960 applies for fittings in accordance with ASTM A234 , ASTM A403 , and ASTM A420.
(b) “S8” appl ies for fittings in accordance with ASTM A81 5.
(c) “SPLD” appl ies for fittings in accordance with ASTM B361 , ASTM B363 , and ASTM B366.
ASME B16.9 Steel Pipe Fittings Dimensions
Why SSM is Your Trusted Supplier of B16.9 Steel Pipe Fittings
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With decades of experience in the industry, SSM offers a wide range of butt-weld fittings that comply with the stringent ASME B16.9 standards. This ensures superior performance and durability in various industrial applications.
Our strict quality control processes, competitive pricing, and dedicated customer service make us the preferred choice for clients seeking reliable, high-quality pipe-fitting solutions.
FAQ
ASME B16.9 pertains to factory-made wrought butt-welding fittings, which are welded to the pipe. ASME B16.11 covers forged fittings, such as socket weld and threaded fittings, used for smaller diameter pipes.
No, ASME B16.9 does not specify pressure ratings for fittings. The fittings are designed to match the pressure ratings of the pipe they are welded to, according to the material and design criteria of the piping system.
Each fitting is marked with the manufacturer’s name or trademark, material identification, nominal pipe size, schedule or wall thickness, and other applicable marks to ensure traceability and quality assurance.
Yes, ASME B16.9 fittings can be used in high-temperature applications if the material selected is suitable for those conditions and meets the relevant design standards.
More information about B16.9 Steel Pipe Fittings:
https://www.asme.org/codes-standards/find-codes-standards/b16-9-factory-made-wrought-buttwelding-fittings
