Oct 6, 2026
Can ER70S-6 Be Used for P22 Steel?
Can ER70S-6 be used for P22 steel? Learn why ER70S-6 is not normally recommended and what to check before using it for P22 welding.
Normally, no. ER70S-6 should not be used as a general-purpose welding wire for P22 steel.
ER70S-6 is a solid carbon-steel welding wire, while P22 is a Cr-Mo alloy steel used in elevated-temperature applications.
The important distinction is simple: ER70S-6 may be able to make a weld on P22, but that does not mean it is suitable for P22 service.
Why Is ER70S-6 Not Normally Used for P22?
P22 welding requires the deposited weld metal to meet the requirements of the joint and its service conditions.
ER70S-6 is primarily intended for carbon and mild steel welding. Its weld-metal system is therefore different from the filler metals normally selected for Cr-Mo steel applications.
Using ER70S-6 on P22 may affect:
- Weld-metal chemistry
- Mechanical properties
- Elevated-temperature performance
- PWHT response
- WPS/PQR qualification
- Code and project compliance
For more background on using carbon-steel wires with Cr-Mo steels, see our guide to carbon steel welding wire for Cr-Mo steel.
This is why visual weld quality alone is not enough to determine whether ER70S-6 is suitable for P22.
Can ER70S-6 Be Used on a P22 Joint?
It can only be considered when the specific application has been evaluated and qualified.
Not every P22 joint has the same requirements. A P22 component may be welded to P22, carbon steel, or another alloy steel. Filler-metal selection can therefore depend on:
- Base-metal combination
- Joint design
- Service temperature
- PWHT requirements
- Required weld-metal properties
- Applicable welding code
- Qualified WPS/PQR
For example, a dissimilar-metal joint may require a different welding strategy from a P22-to-P22 joint.
Therefore, ER70S-6 should not be treated as a universal substitute for the filler metal specified by the welding procedure.
What If ER70S-6 Is the Only Wire Available?
Do not change to ER70S-6 simply because the specified P22 welding wire is unavailable.
Before making a substitution, verify:
- Base materials – What materials are being joined?
- Service conditions – What temperature and service environment will the weld see?
- Weld-metal requirements – Does the deposited metal meet the required properties?
- PWHT – Is post-weld heat treatment required?
- WPS/PQR – Is the proposed consumable covered by the qualified procedure?
- Code and specification – Does the applicable code or project specification permit the proposed filler metal?
If these requirements have not been evaluated, ER70S-6 should not be selected as a simple replacement.
ER70S-6 for P22: Quick Answer
Question | Answer |
|---|---|
Can ER70S-6 physically weld P22? | Yes |
Is it normally recommended for P22? | No |
Is it a general substitute for P22 filler metal? | No |
Can it be used in a qualified application? | Potentially |
Can it be substituted without procedure review? | No |
The key point is:
Weldability does not automatically mean service suitability.
For P22, the filler-metal decision must consider the weld metal, service conditions, heat treatment, applicable code, and qualified welding procedure.
FAQ
Can ER70S-6 be used for P22 steel?
Normally, no. ER70S-6 is primarily a carbon-steel welding wire and should not be considered a general-purpose filler metal for P22.
Can ER70S-6 physically weld P22?
Yes. However, the ability to deposit a sound weld does not prove that the weld metal meets the requirements of the P22 application.
Can I use ER70S-6 if the specified P22 wire is unavailable?
Not automatically. Review the applicable code, project specification, weld-metal requirements, and WPS/PQR before making a substitution.
What is the main concern with ER70S-6 on P22?
The main concern is whether the deposited weld metal provides the required properties and service performance for the P22 component, including after any required PWHT.
Conclusion
ER70S-6 is not normally recommended for P22 steel.
Although it can physically weld P22, its suitability must be established from the weld-metal requirements, service conditions, PWHT, applicable code, and qualified welding procedure.
If ER70S-6 is being considered as an alternative, treat it as a welding procedure and qualification decision—not simply a wire-availability decision.
