The chromium content in alloy 429 is reduced just enough (14-16 percent) to make it more suitable for welding while still retaining its ferritic character. This subtle modification makes it much easier to work with in the production of ferritic stainless steel and gives it a special role in niche heat-resistant and chemical resistor solutions, where welding is more important than maximum corrosion resistance. You can purchase stainless steel 429 ERW pipes and tubes from USA Piping Solution. USA Piping Solution supplies SS 429 ERW pipes and tubes in this low-chromium ferritic grade. For the more common general-purpose ferritic, see our SS 430 ERW page.
Where 429 Fits
429 trades a little of 430's corrosion resistance for better weldability, by running chromium slightly lower. That makes it a specialist rather than a general-purpose grade: it is chosen where a ferritic part needs to be welded and the service is mild enough that the small drop in chromium does not matter. In practice it shows up in certain heat-resisting components and specific chemical-equipment parts. If your requirement is general appliance or trim duty, 430 is the more common and more available choice; if it is a welded heat-resisting part where a specification calls out 429, this is the grade.
Specifications
| Grade / UNS | 429 / UNS S42900 |
| Type | Low-chromium ferritic stainless |
| Chromium | 14.0 – 16.0% (typical, slightly below 430) |
| Nickel | None |
| Tube Standard | ASTM A268; confirm against order |
| Construction | ERW welded |
| Key Property | Improved weldability versus 430 |
Applications
- Welded Heat-Resisting Parts: components where weldability and moderate heat resistance matter.
- Specific Chemical Equipment: parts where a 429 specification is called out.
- Fabricated Ferritic Assemblies: where easier welding than 430 is an advantage.
Choosing Within the Family
429 is a niche grade. For most ferritic tube needs, 430 (general purpose) or 439 (stabilized for welding) will be the better-supported choice, and for exhaust corrosion 436 adds molybdenum. Specify 429 when a drawing or standard names it. Testing follows ASTM A268 with certificates; see our Quality Policy page. Send OD, wall, length, and the governing specification for availability, since 429 is made to order.
Related Products
- SS 430 ERW Pipes & Tubes
- SS 439 ERW Pipes & Tubes
- SS 436 ERW Pipes & Tubes
- Stainless Steel Pipes & Tubes
- Automotive Steel Tubes
Frequently Asked Questions
How is 429 different from 430?
429 runs slightly lower chromium (around 14-16% versus 16-18%), which improves weldability at a small cost in corrosion resistance. 430 is the general-purpose default; 429 is chosen where the weld matters more than the last increment of corrosion resistance.
Is 429 a common stock grade?
It is less common than 430 or 439 and is typically made to order. If your application is general rather than specification-driven, one of the more common ferritics is usually easier to source. Send us the requirement and we will confirm availability.
Can 429 be welded without stabilization?
Its lower chromium helps weldability, but for welded parts that must stay fully corrosion-tight, a stabilized grade like 439 is the more robust choice. Match the grade to how critical the weld-zone corrosion resistance is.