Your current location : home > products > >RESPON Flanges


Most forged steel flanges correspond to the requirements of the American Standards Association (ASME/ANSI Standard B16.5) and the ASTM Specification A-105.

The following types are manufactured:

Welding Neck flanges, available in all pressure ratings and sizes, are butt-welded to the end of the pipe, and are usually specified when service conditions are severe and excellent workmanship necessary.

Slip-on flanges, also available in most pressure ratings and sizes, are a popular type due to their ease of application.

Lap Joint or Van Stone flanges are used on piping equipped with lap joint stub ends or with lapped pipe. They may be used at all pressures and are available in a full size range.

Socket-welding flanges contain a recess in the back of the flange to receive the end of the pipe, which is attached by a fillet weld around the hub of the flange. Since socket-welding connections are not as strong as butt-welded joints, the use of this type of flange is almost always confined to NPS 4 (DN 100) and smaller sizes, and to the lower pressure ratings. Its chief advantage lies in the ease of preparation and installation.

Blind flanges, available in all sizes and pressure ratings, are solid forgings used to close off the end of a piping system and to gain easy access to the interior of the line.



The manufacturing of forged steel flanges is governed by industry standards written by

(1) The American Society for Testing and Materials (ASTM);

(2) The American National Standards Institute (ANSI);

(3) The Manufacturer’s Standardization Society of the Valve and Fittings Industry (MSS);

(4) The American Petroleum Institute (API);

(5) The Canadian Standards Association (CSA);

(6) The American Society of Mechanical Engineers (ASME); and

(7) The Pipe Fabrication Institute (PFI).

They cover specifications for materials, methods of manufacture, dimensions and quality control procedures. CCTF forged steel flanges conform to all applicable standards.


ASTM specifications are, basically, materials specifications. They regulate approved raw materials from which flanges can be made - ingots, or blooms, billets, slabs or bars. In addition, they govern the methods of manufacture, quality control procedures and markings of forged steel flanges.

ASTM specifications are divided into five categories:

A105 - Carbon grades for high temperature service

A181 - Carbon grades for general service

A182 - Alloy and stainless grades for high temperature service

A350 - Carbon and alloy grades for low temperature service

RESPON flanges are available in a wide range of alloy and stainless steels, including grades F304, F304L, F316, F316L. 


ANSI, MSS and API standards govern flange dimensions and tolerances. ASME/ANSI B16.5, titled “Steel Pipe Flanges and Flanged Fittings”, is the basic standard. It covers forged steel flanges, sizes NPS 1/2 (DN 15) through NPS 24 (DN 600).

CSA standard CAN3-Z245 12-M96 covers the manufacture, dimensions, tolerances and material requirements for pipe line flanges.

ASME/ANSI B16.36 covers Orifice flanges. The following MSS, API and AWWA standards are written to supplement B16.5:

MSS SP-6: Flange facings

MSS SP-9: Spot facing for bronze, iron and steel flanges

MSS SP-25: Marking of flanges

MSS SP-39: Bolts and nuts for flanges

API6A: Wellhead equipment

AWWA C207: Hub flanges

The following codes are not flange specifications, but they influences the manufacture of forged steel flanges:

ASME: Boiler and Pressure Vessel Code

ASME/ANSI B31.1: Power Piping

ASME/ANSI B31.3: Petroleum and refinery piping

ASME/ANSI B31.4: Liquid petroleum transportation piping systems

ASME/ANSI B31.5: Refrigeration piping

ASME/ANSI B31.8: Gas transmission and distribution piping systems

ANSI/ASME B36.10M: Standard for wrought steel pipe

ANSI/ASME B36.19M: Standard for stainless steel pipe

ANSI/ASME B16.47: Large diameter pipeline flanges NPS 22 (DN 550) and NPS 26 (DN 650) through NPS 36 (DN900)


Professional Valves & Actuators Manufacturer