Asking for references and case history: what to check

1. What a good reference contains

A strong reference reads like a short engineering record, not a testimonial. Ask the contractor to walk through one case in full. You are checking whether they record their work, not whether they can impress you.

1. The valve type, size class and manufacturer, if the client permits it.
2. The service: fluid, pressure class and any special conditions such as dry gas.
3. The fault found, for example a passing seat, a seized ball or a stem leak.
4. The treatment applied, and the fittings used.
5. The measured outcome, and the test that confirmed it.
6. The date of the work, and the site region.

Client names are often withheld under confidentiality terms. An anonymised case with this level of detail still lets you judge the work. A vague success story does not.

2. Relevance: does the case match your valve

Start with relevance. A case history from a different valve design, size class or service tells you little about your job. A contractor may have strong results on pipeline ball valves and little on the type you operate.

Failure modes also differ between plants. In a risk-based valve integrity study of upstream and midstream sites, published by Valve World, passing seats accounted for 61 per cent of failures, seized valves 28 per cent, external leakage 6 per cent and other modes 5 per cent. Distributions vary by population, so check your own maintenance records and ask for cases that match your dominant faults.

Match the service as well as the valve. Dry gas, sour service and high temperature each change the chemistry and the risk. If you are evaluating us, apply the same tests: ask for case detail that matches your valve type, size class and service, and for how each outcome was confirmed. Our case studies directory is the starting point. Use it to test relevance before you ask us for more.

3. Evidence grade: how the outcome was proven

Next, grade the evidence behind the claimed outcome. Ask one question of every case: how do you know it worked? The answer separates engineering records from marketing.

For a passing valve, the confirming field test is a seat-leak test under agreed conditions. That may be pressure decay across the closed valve, double block and bleed monitoring, or a witnessed leak test. Sound, bubbles and flow indication are screening signs. They suggest a result but never prove one.

Watch for standards quoted in the wrong place. API 598 and ISO 5208 are factory acceptance references for leakage testing, not field results. A contractor who presents them as proof of a field repair has not understood the evidence. Our guide to choosing an online valve maintenance provider covers this evaluation in full.

4. Recency and what changed since

Recency is the third test. Valves, sealant formulations and field crews all change over time. A case from many years ago shows experience, but it may not describe what you would buy today.

1. Ask when each case was completed, to the month if possible.
2. Ask whether the same product line is still made, or has been reformulated.
3. Ask whether the engineers named on the job still work on such jobs.
4. Ask what the contractor has changed in method since, and why.

Current certificates matter the same way. ISO certification tells you a system is audited and current, though it does not prove field skill on your valve type. We make our cleaners, lubricants and sealants in-house, so you can ask us what changed, and when.

5. When the evidence falls short

A short reference list is not automatically disqualifying. Small specialist firms often cannot publish client names, and a confidentiality restriction is not a warning sign by itself. What matters is whether technical detail exists behind the summary.

Some caution is still wise. Treat these as warning signs: outcomes with no stated test, cases that cannot be dated, and refusals to explain method. You can also test a weak reference set directly.

1. Run a capability audit covering products, equipment, people and records.
2. Check the years and valve types behind the claims, as our article on verifying experience claims sets out.
3. Commission a small condition survey on a few valves, with the acceptance test agreed in writing first.

If the evidence stays thin after that, a wider search is the honest answer. A small trial on your own valves, with the test agreed in advance, is evidence no case history can match.