E-mail: authentic013@steelpipes-fitting.com
WhatsApp: +86 13668807131
E-mail: authentic013@steelpipes-fitting.com
WhatsApp: +86 13668807131
Mar. 31, 2026
Fitting dimensions are always consistent with the connecting pipe dimensions.
Fitting dimensions are related to pipe dimensions and are expressed as nominal pipe size (NPS) and nominal diameter (DN).
Thickness is indicated by the appendix number. Fittings are typically thicker than the pipe to avoid scrap due to thickness reduction during manufacturing. To prevent mismatch between the fitting's inner diameter and the pipe's inner diameter, the manufacturer will bevele the inner edge of the fitting.
Fittings are classified according to their pressure and temperature ratings: Socket weld and threaded joint sizes range from NPS 1/8” to 4”. Weld-to-button fittings are available in the following pressure-temperature ratings:
2000 (threaded fittings only)
3000 and 6000 (two types)
9000 (socket weld joints only)
Standards for checking fitting dimensions:
For pipe fitting products (WP), the following sizes are covered:
ASME B16.9 - Standard for factory-manufactured weld-to-button fittings in NPS 1/₂ to NPS 48” sizes;
ASME B16.28 - Standard for forged steel weld-to-button short-radius elbows and return pipes in NPS 1/₂ to NPS 24” sizes.
For weld-to-button fittings, the following size is covered:
ASME B16.11 - Standard for forged steel fittings, covering both socket weld and threaded fittings.
What should be checked during fitting dimension inspection?
When inspecting pipe fitting dimensions, the following should be confirmed:
Diameter
Length
Thickness chart number
Straightness and perpendicularity of fitting ends
Degree of elbows and bends
Gearbox concentricity
Fit dimensional inspection
Fit material
Fits are always connected to pipes; therefore, the chemical and mechanical properties of these materials must be matched to the pipe materials.
Fits are available in different grades to match pipe materials such as carbon steel, alloy steel, and stainless steel, as well as special materials such as titanium and copper alloys.
ASME B16.9 & 16.28 provide a list of materials used in the manufacture of butt-welded pipe fittings.
ASME B16.34 provides a list of materials used in the manufacture of butt-welded pipe fittings according to ASME B16.11.
ASME B16.9 is the standard for factory-manufactured butt-welded pipe fittings; ASME B16.28 is the standard for butt-welded short-radius elbows and bends;
ASME B16.11 is the standard for forged steel socket weld and threaded fittings. It refers to another ASME material standard, ASME B16.34, for flanges, threads, and welded-end valves.
If fittings are manufactured according to ASME B16.9 and B16.28, the material grade should be prefixed with WP.
This section lists commonly used material grades for pipe fittings:
For carbon steel: - ASTM A234 Gr.WPA/B, ASTM A420 Gr.WPL6
For alloy steel: - ASTM A234 WP1 / WP5 / WP7 / WP9 / WP11 / WP12 / WP22
For stainless steel: - ASTM A403 WP304 / WP304L / WP304H / WP316 / WP316L / WP321 / WP347
Latest News
Industry News
Sep. 20, 2026
Why are dimensions and wall thickness so important when purchasing carbon steel pipe fittings?
In piping engineering, although carbon steel pipe fittings are small in size, they directly impact the connectivity, pressure-bearing capacity, and operational stability of the piping system. When purchasing, buyers should not focus solely on price; dimensional accuracy and wall thickness control are equally critical indicators.
Industry News
Sep. 16, 2026
In industrial pipeline projects such as oil and gas, chemical, power, shipbuilding, and construction, carbon steel pipe fittings, although merely connecting components within the pipeline system, directly impact the system's installation, sealing, and long-term operation.
Industry News
Sep. 14, 2026
Working Principle of Carbon Steel Flanges
Cast flanges feature rough external shapes but precise dimensions, require minimal machining, and offer low costs; however, they are prone to casting defects (such as porosity) and cracks (often due to inclusions), and their internal structure is suboptimal (resulting in poor grain flow characteristics after cutting).
Authentic is here to help you find the right pipe fittings and flanges for your specific needs.
FAQ
What certifications do your products have?
Our products comply with international standards such as ASTM, ANSI, JIS, DIN, and GB. We also hold various certifications to assure quality and reliability, including ISO 9001.
How can I get some samples?
If you need, we will offer you samples for free, but new customers are expected to pay express charge.
To which country have you supplied your products?
We have supplied to Thailand, China Taiwan, Vietnam, India, South Africa, Sudan, Peru, USA, Brazil, Trinidad and Tobago, Kuwait, Qatar, Sri Lanka, Pakistan, Romania, France, Spain, Germany, Belgium, Ukraine etc. (Figures here only include our customers in latest 5 years.)
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Our team at Authentic is here to help you find the right pipe fittings and flanges for your specific needs.
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authentic013@steelpipes-fitting.com
+86 13668807131
Donghe Industrial Zone, Mengcun County, Cangzhou City, Hebei Province
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