Short answer: Weld quality on a stainless steel eyewash station is decided by four checks: penetration and finish at the joint, pickling and passivation of the heat-affected zone, a pressure test at the working pressure, and a flow test that confirms the pattern after assembly. Skip the second one and the unit can look perfect and still corrode at the weld within a season.

Why the weld is the weak point

Stainless steel protects itself with a passive chromium oxide layer. Welding destroys that layer in and around the joint and leaves a heat-affected zone that is depleted in chromium and rich in surface contamination. In a chloride environment - which is exactly where eyewash stations live, next to chemical processes - that zone is where pitting starts.

A brushed-off weld looks acceptable and behaves badly. The visible symptom arrives months later as a rust streak under the bowl, usually reported by the customer rather than found by the maker.

The four checks

Material choice is part of the answer

304 stainless covers most indoor industrial and laboratory installations. For chloride-rich environments - coastal sites, brine handling, certain chemical processes - 316 is the correct choice, and no amount of weld finishing makes 304 behave like 316.

The same logic applies to the pipe. Horn bends and 90-degree bends formed from seamless pipe avoid the seam that becomes the starting point for a crack under pressure cycling. A welded elbow in a thin-wall line is a future failure with a date on it.

What we ask customers before choosing a grade

• What chemicals are present, and at what concentration

• Indoor or outdoor, and how far from the coast

• Ambient temperature range, including freezing

• Cleaning regime - some sanitising agents are aggressive to 304

Four questions, and they usually settle the grade before price is discussed.

Frequently asked questions

Can I specify 316 for everything to be safe?

It works, and it costs more. For dry indoor sites with no chlorides, 304 with proper passivation performs well over a long service life.

Does a pressure test prove the weld is good?

It proves the assembly holds at test pressure today. It does not prove the passive layer survived. Both checks are needed.

How do I verify passivation on delivery?

Ask for the process record, and inspect for heat tint at the joints. A blue or brown discolouration around a weld indicates the oxide was not removed.

What is the most common warranty claim on stainless units?

Surface corrosion at welds in chloride environments where 304 was specified, or where the joints were not properly treated after welding.

See the difference on a sample

We are happy to send weld and finish detail photographs for any model in the eyewash range, including the stainless steel pedestal units. If you have a corrosive installation, send us the chemical list and we will recommend the grade in writing before you order.

Note: workshop figures and test equipment descriptions are confirmed against current production records; ask our sales team for the latest test report format.