Flanges for US refineries and petrochemical plants
Refineries and petrochemical plants on the Gulf Coast run some of the most demanding process piping anywhere: high temperatures, hydrocarbons, turnarounds that need parts on a fixed date. Here is how flanges are specified for them.
Refinery and petrochemical piping is built to ASME B31.3 and uses weld neck flanges to ASME B16.5 and B16.47, orifice flanges to ASME B16.36 at flow meters, spectacle blinds for positive isolation, and ring type joint facing in the higher classes, in carbon steel A105 and A350 LF2, stainless 304L, 316L, 321 and 347, and duplex. We make all of these, check every stainless flange by PMI, and ship each heat with an EN 10204 3.1 mill test report. Indian refiners we have supplied include Indian Oil, BPCL, HPCL, Chennai Petroleum and Reliance Industries.
Where flanges are used in refining and petrochemical
| System | Flange | Class and material |
|---|---|---|
| Crude and vacuum units, cokers | Weld neck RF and RTJ, high temperature grades | Class 300 to 1500, A105, 321, 347 |
| Hydrotreaters and hydrocrackers | Weld neck RTJ in the high pressure loop | Class 900 to 2500, stainless and alloy grades |
| Flow metering | Orifice flanges to ASME B16.36 with pressure taps | Class 300 to 2500, A105 or 316L |
| Isolation for maintenance and turnarounds | Spectacle blinds, spacers and blanks | Class 150 to 900 |
| Steam, condensate and cooling water utilities | Weld neck and slip-on RF | Class 150 to 600, A105 |
| Corrosive and chloride service | Weld neck or lap joint with stub end | 316L, duplex S32205, super duplex S32750 |
ASME B31.3 and the flange standards it calls up
ASME B31.3 lists the component standards it accepts. For flanges these are ASME B16.5 up to NPS 24 and B16.47 above it, B16.36 for orifice flanges and B16.48 for line blanks. The pressure-temperature ratings in B16.5 and B16.47 set how high a class each line needs at its design temperature: a 600 °F hydrocarbon line that would be Class 150 at ambient temperature may need Class 300.
| Standard | Covers | Our supply |
|---|---|---|
| ASME B16.5 | NPS 1/2 to 24, Class 150 to 2500 | Weld neck, slip-on, blind, socket weld, threaded, lap joint; RF, FF and RTJ |
| ASME B16.47 | NPS 26 to 60, Series A and B | Weld neck and blind, Class 75 to 900 |
| ASME B16.36 | Orifice flanges | Weld neck, slip-on and threaded, Class 300 to 2500 |
| Line blanks | Spectacle blinds, spacers and blanks | Class 150 to 900 |
Positive material identification
A carbon steel flange installed by mistake in an alloy line is a known cause of refinery failures, which is why API RP 578 sets out a material verification program for alloy piping. We check every stainless and alloy flange with our own Bruker PMI analyzer and record the result on the certificate, and the heat number stamped on each flange ties it to its mill test report.
Materials for hot and corrosive service
| Grade | Specification | Why it is chosen |
|---|---|---|
| A105 | ASTM A105 | Carbon steel for most hydrocarbon, steam and utility lines |
| A350 LF2 | ASTM A350 | Impact tested at -50 °F for cold service, flare and blowdown lines |
| F321, F347 | ASTM A182 | Stabilized stainless steel for high temperature service where 304 could sensitize |
| F304L, F316L | ASTM A182 | Corrosive and product purity service, caustic and amine units |
| Duplex S32205, super duplex S32750 | ASTM A182 F60 and F53 | Chloride-bearing cooling water and process streams |
Stainless flanges can be supplied pickled and passivated to ASTM A380 and A967, and tested for intergranular corrosion to ASTM A262 Practice E on request.
Ordering for a US project
Send your line list with the standard, type, size, class, bore or schedule, facing, material and quantity for each line, and we quote every line as specified. Every order ships from our works in Gujarat, India; we have no US office or warehouse. Each line is supplied to your line list, and ordering from India explains the documents, marking, packing and customs.
Frequently asked questions
Do you make orifice flanges?
Yes, to ASME B16.36: weld neck, slip-on and threaded orifice flanges in Class 300 to 2500, with the pressure tap holes drilled and tapped. Send the meter size, class, bore and tap size.
Can you supply spectacle blinds for a turnaround?
Yes. Spectacle blinds, spacers and blanks in Class 150 to 900, matched to the flange facing on each line. List them with the flanges so one quotation covers the package.
Can a third-party inspector witness the tests?
Yes. Your inspector or agency can witness PMI, dimensional checks and final inspection at our works; TÜV, Gulf Lloyds, IRClass, Bureau Veritas and SGS have inspected our material. With their sign-off we issue EN 10204 3.2 certificates.
Sources
- ASME B31.3, Process Piping
- ASME B16.5, Pipe Flanges and Flanged Fittings, NPS 1/2 through NPS 24
- ASME B16.47, Large Diameter Steel Flanges, NPS 26 through NPS 60
- ASME B16.36, Orifice Flanges
- ASME B16.48, Line Blanks
- API RP 578, Guidelines for a Material Verification Program (MVP) for New and Existing Assets
- ASTM A262, Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels