MSS SP-43
Wrought and fabricated butt-welding fittings for low-pressure, corrosion-resistant service
Covers wrought and fabricated buttwelding fittings for low-pressure, corrosion-resistant service — typically thin-wall stainless fittings in schedules 5S and 10S, and stub ends for lap-joint flanges.
- Dimensional standards
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What to know before ordering to MSS SP-43
The points that decide whether material to MSS SP-43 is accepted at inspection.
- SP-43 fittings are rated for lower pressure than B16.9 fittings.
- Fittings to SP-43 are marked Class CR under ASTM A403 or A815.
- Short-pattern (MSS) stub ends are defined here; long-pattern stub ends are in ASME B16.9.
Products made to MSS SP-43
How MSS SP-43 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Related standards
MSS SP-43 — questions buyers ask
What does MSS SP-43 cover?
Covers wrought and fabricated buttwelding fittings for low-pressure, corrosion-resistant service — typically thin-wall stainless fittings in schedules 5S and 10S, and stub ends for lap-joint flanges.
Does MSS SP-43 specify the material?
No. MSS SP-43 sets dimensions; the material comes from a separate specification such as ASTM A182, A105 or B564 for flanges, or A403 and B366 for fittings. A complete order names both.
Do you supply certificates to this standard?
Yes. Material is supplied with mill test certificates to EN 10204 3.1 showing the standard, grade and heat number; 3.2 with third-party inspection on request.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026