Tank inspection services: separating the examination from everything around it

A firm selling tank inspection services may be offering any combination of half a dozen activities, and the proposals rarely draw the line in the same place. The examination itself is often the smallest line on the page. Everything around it, getting the tank ready and dealing with what is found, is where the schedule and the budget live.

The examination, which is the short part

Visual work, thickness readings, floor scanning where applicable, examination of welds, roof, nozzles, appurtenances and foundation, and a report. On an in-service external examination this can be a matter of days. It is the part people picture when they use the phrase, and the part that determines the least about the final invoice.

Getting the tank ready, which is the long part

For an internal examination the tank has to come out of service, be emptied, cleaned, gas-freed and made safe to enter, and the waste from that cleaning has to go somewhere. Scaffolding or rope access has to be arranged for the shell. None of this is inspection and all of it is on the critical path. Which party is responsible for each item is the single most useful thing to fix in writing before bids go out.

The engineering, which is a separate skill

Turning readings into a fitness-for-service conclusion, calculating minimum required thickness, deriving a corrosion rate and setting the next due date is engineering work. Some firms do it in house and some subcontract it, and either is fine so long as the proposal says so and names who signs. What is in that conclusion is described on the tank integrity assessment page.

Repairs, and the conflict nobody mentions

A firm that inspects and also repairs has an obvious interest in what the inspection finds. That is not a reason to exclude them, and integrated delivery genuinely saves mobilizations. It is a reason to say in the scope how findings will be handled, whether a second opinion is available on major repair recommendations, and how repair work will be priced if it arises. The same question applies in reverse to a firm that only inspects: it has no incentive to find work, but it also has no obligation to stay involved once the report is issued, and somebody still has to turn the repair list into a plan.

Who signs, and whether they are current

An in-service inspection report carries an individual credential, not a company logo, and the credential expires. Asking for the name and number of the person who will sign, and checking it before award rather than after, takes minutes. The method is set out on the page on verifying an inspector.

Mobilization, and why batching tanks pays

A crew, its equipment and its access arrangements have to get to the site, and that cost is largely independent of how many tanks are examined once they are there. A site with six tanks that schedules them one a year pays six mobilizations. A site that groups examinations, where the calculated intervals allow it, pays fewer. This is one of the few places where an owner can genuinely reduce the total without reducing the scope, and it is a planning decision rather than a procurement one.

Making three bids comparable

Issue one scope document to all bidders and require them to price against it, listing exclusions explicitly rather than by omission. Ask each to state what is not included. The cheapest bid on an unscoped job is almost always the one that assumed the least about cleaning, access and reporting, and the difference reappears once the tank is open. The fields that have to be filled in first are those in the scope specification.