The Golden Rules of Stainless Steel Flange supply
Flanges are amongst the most critical components in a pipeline. They are used as connections for pumps, valves, strainers etc. and for pipework which has to be regularly dis-assembled and re-assembled.
It is critical that the correct flanges are supplied that can cope with the pressure of the system and are compatible with all the components which are connected in the pipeline. A flange is specified by the nominal pipe size and the pressure rating. However, there are distinctly different types of flanges depending on the plant design. In the offshore, petro-chemical, power and nuclear power industries they are generally designed in the USA, UK or Germany. There are of course flanges required for the paper pulp, water, brewery industries etc. but the rules of suitability remain the same.
Those who are regularly involved in the buying and selling of flanges, will be all too aware of how easy it is to supply the wrong flange if the correct questions are not asked. In this short piece we outline the do’s to supply the correct flange which will avoid delay, frustration and most importantly costly mistakes!
Listed is a short tick list of the relevant questions for the correct identification of a flange
Golden rules for flange identification
- Stainless Steel Grade: 304L, 316L, 1.4306, 1.4404, 31803, 254SMO, UNS 31254 etc.
- Pipe Size: NB (Nominal Bore), NPS (Nominal Pipe Size), DN (Diameter Nominal)
- Dimensional specification: ASME B16.5, EN1092-1, BS4504, BS10, API605 etc.
- Pressure Ratings: 150#, PN16, Table E etc.
- Type of Face: RF (Raise Face), FF (Flat Face), RTJ (Ring Type Joint) etc.
- Quantity Required
- There is no such thing as a ‘better grade’ of steel, and a higher price does not mean better quality or performance. Instead steel is manufactured to internationally recognised specifications to fulfil a particular application. Material grades may or may not be interchangeable, but it is essential that the grade of steel is fit for purpose. You must find out exactly what grade of material is acceptable before supplying or purchasing a stainless steel flange.
- Flanges of different dimensional specifications and pressure ratings are not interchangeable.
Flange manufacturing materials
|Dimensions||Base Material||Pressure Rating|
|ASME B16.5||ASTM A182 (Forgings) ASTM A240 (Plate)||150#. 300#. 400#. 600#. 900#. 1500#. 2500#.|
|API 605||ASTM A182 (Forgings) ASTM A240 (Plate)||150#. 300#. 400#. 600#. 900#. 1500#. 2500#.|
|ASME B16.47series A & B||ASTM A182 (Forgings) ASTM A240 (Plate)||150#. 300#. 400#. 600#. 900#. 1500#. 2500#.|
|EN1092-1||ASTM A182 (Forgings)||PN2.5. PN6. PN10. PN16. PN25. PN40. PN63. PN100. PN160. PN250. PN320. PN400.|
|BS4504||BS970 (Bar)ASTM A240 (Plate) ASTM A182 (Forgings)||PN2.5. PN6. PN10. PN16. PN25. PN40. PN63. PN100. PN160.|
|BS10||BS970 (Bar)ASTM A240 (Plate) ASTM A182 (Forgings)||Table D. Table E. Table F. Table H. Table J. Table K. Table R. Table S. Table T.|
Typical Stainless Steel 18/8 Grade Designations
|304||304S15||X5 Cr Ni 18 10||1.4301|
|304L||304S11||X2 Cr Ni 18 9||1.4307|
|316||316S31||X5 Cr Ni Mo 17 12 2||1.4401|
|316L||316S11||X2 Cr Ni Mo 17 13 2||1.4404|
|321||321S31||X6 Cr Ni 18 10||1.4541|
|316Ti||320S31||X6 Cr Ni Mo Ti 17 12 2||1.4571|
|SMO||254SMO||X1 Cr Ni Mo Cu N 20 18 7||1.4547|
The information contained in this article is intended to help you to supply the correct flanges contained in the golden rules. It is not intended as a comprehensive guide to all the flanges that are available.
IF YOU ARE NOT SURE THAT YOU HAVE ALL THE INFORMATION TO SUPPLY THE CORRECT FLANGE ALWAYS REFER BACK TO THE CLIENT AND THE SPECIFICATION.
Should you like to send you next enquiry for stainless steel flanges to Stock Services, please send us an email.