The 57Y03 back cap is a replacement TIG torch back cap listed for WP17, WP18 and WP26 style air-cooled torches. It is a cheap consumable that seals the back of the torch head and protects the tungsten, so buy it only if the length and fit match your torch. This review is built from the Amazon listing and does not claim hands-on testing.
Quick Verdict
Verdict: A simple replacement part for WP17, WP18 and WP26 torches, as long as you pick the right back cap length.
Best for: TIG welders replacing a cracked, lost or wrong-length back cap.
Skip it if: your torch is a different series, or you need a long cap to fit full-length tungsten.
57Y03 back cap: key specs
Details below are from the listing. Confirm pack count, size and material on the current page before you order.
| Specification | Detail |
|---|---|
| Part number | 57Y03 |
| Part type | TIG torch back cap |
| Listed fit | WP17, WP18 and WP26 series torches |
| Length | 57Y03 is commonly sold as the medium cap in the 57Y series (long is 57Y02, short is 57Y04). Check the listing for the exact length. |
| Listed weight | 2.39 oz (may include more than one cap, check the pack count) |
| Material | Check the listing. Back caps are often rubber or plastic. |
| ASIN | B09N323HNK |
What a TIG back cap does
The back cap screws onto the rear of the torch head. It clamps the tungsten collet body in place and keeps shielding gas from leaking out the back. The cap length decides how long a tungsten you can fit:
- Long cap (57Y02): fits full-length tungsten, easiest for most welders.
- Medium cap (57Y03): fits a shorter tungsten, but gives better access in tight spots.
- Short cap (57Y04): for very tight access, with a short tungsten stub.
Pick the length that matches how you weld. If you use full-length tungsten, a medium cap can be too short to close the torch.
How to check it fits your torch
- Confirm your torch is a WP17, WP18 or WP26 style head. Torches like WP9 or WP20 use different parts.
- Check the thread and O-ring on your old cap. A damaged O-ring is a common cause of gas leaks.
- Decide on cap length: long, medium or short.
- Check the pack count so you do not buy more or fewer caps than you need.
- Match the cap to the collet body and collet size you run.
Pros
- Cheap replacement for a common wear part.
- Listed to fit WP17, WP18 and WP26 style torches.
- Medium length helps with access compared with a long cap.
- Small and easy to keep as a spare.
Limitations
- Medium length limits tungsten length.
- Material and pack count must be checked on the listing.
- Fit is not guaranteed on non-standard or proprietary torches.
- Worn O-rings or collet bodies can still leak, even with a new cap.
Install and maintenance tips
- Let the torch cool and shut off the gas before changing the cap.
- Check the O-ring for cracks and replace it if it looks worn.
- Do not overtighten. Hand-tight plus a small snug turn is enough.
- Keep a spare cap in your kit next to spare collets and collet bodies.
- After fitting, test for gas leaks by listening and checking the arc for gray or sooty welds.
Alternatives and related guides
Compare other back caps in our RIVERWELD TIG back caps review and the Mtsooning 41V35 back cap. For a bigger set of parts, see the 63-piece TIG torch accessories kit for WP-17, 18 and 26, or the WP17 TIG welding torch review.
Frequently Asked Questions
What torches does the 57Y03 back cap fit?
It is listed for WP17, WP18 and WP26 series air-cooled TIG torches. Check your torch head and the old cap before ordering.
Is the 57Y03 a long, medium or short back cap?
In the common 57Y numbering, 57Y02 is long, 57Y03 is medium and 57Y04 is short. Check the listing for the exact length of this product.
Do I need to replace the O-ring too?
If the O-ring is cracked or flat, replace it. A worn O-ring is a common source of gas leaks and porosity.
Can I use a medium cap with full-length tungsten?
Usually not. Full-length tungsten needs a long cap, so use a medium or short cap with a shorter tungsten.
Does a back cap affect weld quality?
A leaking or poorly seated cap can let air into the shielding gas and cause porosity or a gray, sooty weld. A good cap and O-ring keep the gas sealed.
Final verdict
The 57Y03 back cap is a cheap, simple spare for WP17, WP18 and WP26 torches. Check the cap length, material and pack count on the listing so it matches your tungsten length and torch before you buy.
