If you already run Standard Press copper, you own V-profile jaws. The new 316 stainless press range is M-profile, so those jaws can't press it. Every stainless listing says the same thing: use M-profile jaws only. This is the single most important thing to sort out before quoting your first stainless job.
Two Standard Press systems, two profiles
| Copper (water, solar) | 316 stainless | |
|---|---|---|
| Press profile | V-profile | M-profile |
| Tube | Copper tube | 304/316 stainless tube to AS 5200.053 |
| Size range | Common trade sizes | 15mm to 168.3mm |
| Standard seal | Black EPDM (red FKM on solar) | Black EPDM |
We covered how press profiles work in V-profile vs M-profile press jaws. In short: the jaw closes on a bead around the seal, and the jaw's contour has to match the bead so the force deforms it the way the fitting was designed. A mismatched jaw can leave a joint that looks pressed but isn't sealed as intended.
Why the jaw is the problem, not the tool
Most press tool bodies take interchangeable jaws, so the tool you use for copper may well drive stainless jaws. Three things decide whether it will:
- Profile. It has to be M-profile for this range.
- Material approval. Stainless is harder than copper. Tool and jaw makers state which fitting materials and systems their jaws are approved for, so check that your tool and the M-profile jaws are approved for stainless press before you rely on them.
- Size. Smaller jaws usually cover roughly 15mm to 35mm or so. Larger sizes in this range (42mm, 54mm and up to 108mm and 168.3mm) typically need larger jaws, collars with an adaptor jaw, or a higher-force tool. Check what your tool maker offers for each size you'll press.
Don't assume a jaw set covers everything because it's the right profile. Read the stamping on each jaw for size and profile.
Pressing stainless: the same discipline, less forgiveness
- Cut square with a cutter made for stainless tube, then deburr inside and out. A burr can nick the EPDM seal as the tube goes in.
- Check the seal is present, seated and the right colour for the service. Black is EPDM for water. See choosing the ring seal for stainless press.
- Mark the insertion depth and insert to the mark. The stainless coupling has a centre stop; the slip coupling doesn't, so mark carefully on repairs.
- Hold the jaw square over the bead and complete the full press cycle.
- A bad press is cut out, not re-pressed.
Is it worth buying M-profile jaws?
If stainless is a one-off, hiring may make more sense than buying. If you're doing coastal, commercial kitchen, process or plant room work regularly, the jaws pay for themselves quickly against welding or threading. We weigh the bigger cost question in stainless press vs copper press.
One more thing to keep separate on the van: copper and stainless fittings look similar at a glance in a dark ute tray. Keep them in separate boxes, and keep the V and M jaws clearly labelled.
Frequently Asked Questions
What press profile are Standard Press stainless fittings?
M-profile. Every 316 stainless press listing specifies M-profile jaws only. Standard Press copper fittings are V-profile.
Can I press stainless fittings with my copper press jaws?
Not with V-profile jaws. You need M-profile jaws, and you should confirm with the tool maker that the tool and jaws are approved for stainless press systems.
Can one press tool do both copper and stainless?
Often the tool body can, with the right jaws fitted for each system. Check the tool maker's approvals for stainless and the size range each jaw covers.
Do larger stainless sizes need different jaws?
Usually. Larger diameters typically need larger jaws, collars with an adaptor jaw or a higher-force tool. Check your tool maker's options for each size you'll press.