Pipe Flanges

China flange supplier · ASME B16.5 & B16.47

Carbon, low-temperature, alloy and stainless flanges for oil, gas and water projects — by the piece, with the mill named on the quotation.

• Stock5–10 days
• Made to order3–5 weeks
• MinimumBy piece, none on standard items
• TestingSGS, BV or TUV on request

Get a quote in 1 business dayWhatsApp a specification

• Standards: ASME B16.5 · ASME B16.47 · ASTM A105 · ASTM A182 · ASTM A350 · MSS SP-44 · ASME B16.9 · ASTM A694
• 8 products in this line · 7 flange types
• Certificate: EN 10204 3.1 with every order, 3.2 on request

As a flange supplier, Mejor Steel supplies pipe flanges from China to ASME B16.5 and B16.47, in carbon, low-temperature, alloy, stainless and duplex grades, with the types, facings and class ratings set out on this page.

What this line covers, and which page carries it

Seven flange types cover this line, and the type is settled by how the flange joins the pipe and by the service. The table routes the enquiry to the page that carries the detail.

The stub end for a lap joint flange is ordered with the flange, not instead of it.

What we supply: sizes, classes and facings

The table is the size, pressure class and facing range for this line, from 1/2 in to 60 in (DN15 to DN1500). Materials follow the pipe and the service — carbon A105, low-temperature A350 LF2, high-strength A694, alloy F11/F22/F91 and stainless F304/F316 — with the full grade list on each flange page.

Nickel-alloy flanges are supplied where the project calls for them: Inconel flanges are quoted against your drawing or datasheet, with the mill test certificate and, where the project asks for it, third-party inspection before shipment.

Class 150 dimensions, NPS 1/2 to 12 in (ASME B16.5)

Outside diameter, thickness, bolt circle and bolt size for the common sizes. Thickness includes the 1.6 mm raised face, and the same dimensions apply to weld neck, slip-on, blind, socket weld and threaded flanges at Class 150.

Full table to NPS 24 in, with raised-face diameters: ASME B16.5 flange dimensions. Above 24 in: B16.47 Series A dimensions.

Data sheet: Pipe flanges (PDF) · Full Class 150 table

MS flanges: mild steel flanges to ASME B16.5

An MS flange — mild steel flange — is the everyday term for a carbon steel flange to ASTM A105, the default grade for general and moderate-temperature service. The term is common in India, the Middle East and South-East Asia, and on the shop floor it means the same part: a forged carbon steel flange in the same weld neck, slip-on, blind and threaded types listed on this page, to the same ASME B16.5 dimensions and pressure classes. Where the enquiry says MS flange, Mejor Steel quotes A105 with the mill test certificate and the facing, class and bore stated on the drawing or datasheet.

MS flange and carbon steel flange are used interchangeably on this line; if the project specification calls for a low-temperature or high-yield grade, the A350 LF2 or A694 page applies instead.

Stainless flanges: the same types, a different material specification

Stainless flanges are supplied in the same seven types on this line, and on the same ASME B16.5 and B16.47 dimensions. What changes is the material specification, and it is worth stating on the enquiry because it decides which grade page the certificate follows. SS 304 and SS 316 are the common shorthand for the same F304/304L and F316/316L grades under ASTM A182, and either designation on the enquiry will reach the same material.

A stainless flange is a forged fitting, so the grade page to read is ASTM A182 F316 flange, which covers the F304 and F316 comparison and the pressure–temperature ratings that go with the class. Where the line is specified in 904L rather than a 300 series grade, the grade is covered on 904L stainless steel pipe.

What to settle before a flange can be priced

Four things decide the part, and the order they are settled in matters. The pressure class, from 150 to 2500, sets the wall and the bolt circle. The facing — raised face, flat face or ring joint — has to match the gasket and the flange it bolts to. The bore has to suit the pipe: a slip-on takes the pipe outside diameter, a weld neck is bored to match the pipe wall, and a threaded or socket weld connection follows the thread standard instead. The material follows the pipe and the service.

The class is a rating, not a pressure

Class 150, 300, 600 and upwards are ASME B16.5 designations rather than pressures in psi. The allowable pressure at the working temperature is read from the B16.5 pressure–temperature table for the material group, so the same Class 150 flange does not carry the same allowance in carbon steel as it does in stainless. The group tables are on the grade pages linked above.

Which gasket pairs with which facing is set out on the individual flange pages, because it depends on the joint rather than the line.

Where flange orders go wrong

The five mistakes below all end in a flange that will not bolt up, will not seal, or does not match the pipe.

Frequently asked questions

Orifice Flanges

An orifice set is a pair of flanges that holds an orifice plate between them, so that the pressure drop across the plate can be measured and the flow calculated. The pair is made to ASME B16.36 rather than to B16.5, because the dimensional requirements are different: each flange carries a pair of pressure taps, the plate is located by a raised or recessed face, and jack screws are fitted so the plate can be changed, and the pair opened, without springing the line.

Three things have to be fixed before an orifice flange can be quoted: the facing (raised face or ring joint), the tap type and position (flange taps to B16.36, or corner, pipe or vena contracta taps where the project specifies them), and whether the plate holder is integral with the flange or a separate wafer. Pressure class and size follow the line and the project specification, the same way they do for the rest of the flange set.

Orifice assemblies are quoted against your drawing or datasheet, with the mill test certificate to EN 10204 3.1 and, where the project asks for it, third-party inspection before shipment.

What decides the price

There is no list price for flanges: the same drawing can be quoted at different numbers depending on seven things. Send them and the quotation comes back within one business day.

Reply within one business day. Send the seven items above with the quantity and the destination port. Send the specification or WhatsApp the specification.