CSA vs ASTM Bolting: What Canadian Projects Actually Specify

The short answer

Most Canadian oil, gas and process projects specify pressure bolting to ASTM / ASME standards (ASTM A193, A320, A194 and ASME B16.5 / B16.47 flanges), while CSA standards govern areas such as structural steel, pressure equipment registration and pipeline systems. Your project specification decides which applies to each joint.

Where ASTM applies

Flanged piping, pressure vessels and heat exchangers on Canadian plants are typically designed to ASME codes, so bolting is called up as ASTM A193 B7, A320 L7 or B7M for sour service, with A194 nuts.

Where CSA applies

CSA standards commonly govern structural connections, pipeline systems and provincial pressure equipment registration. Where a CSA standard references ASTM materials, the bolting is still supplied and certified to the referenced ASTM grade.

What procurement should check

• The exact grade, class and nut pairing on the datasheet
• Impact-test temperature for cold service
• NACE MR0175 / ISO 15156 requirements for sour gas
• Certification level: EN 10204 3.1 or 3.2

If the specification is unclear, send it with your RFQ and we will confirm the grade before quoting. See our Canada fastener supply page.