Keep heat-transfer-system repairs uneventful

A good plan is the key to avoiding risks in the maintenance of systems using high-temperature organic fluids.

By Conrad E. Gamble, Solutia Inc.

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Drain into compatible containers (hose, buckets).

Return all plugs, flange blinds, etc., after completion.

Minimize spark generation and monitor atmosphere with explosion meter.

Repair with compatible or like-for-like parts.

Fully depressurize equipment prior to opening system.

Develop and execute the plan
When developing a repair plan for a heat transfer system, there are seven steps to follow.
Identify the needs for repair: Many processes run with a high on-stream time. In such cases, unplanned shutdowns generally occur only for unavoidable repairs that will define the primary intent of the job scope. However, the downtime may enable taking care of other items. Keep a list of secondary items that don’t require immediate correction so they can be addressed at the first available opportunity. These secondary items might include insulation repairs, valve stem packing repairs, gasket replacement, equipment inspections, instrument calibrations and interlock checks.

Downtime should be used as effectively as possible, so materials should be acquired in advance to maximize the amount of work that can be completed.

Assess the root cause of failure: Root cause assessment should be made for each failure to determine and correct its cause. This helps ensure a repair is made only once for a given item. Several common failure modes and possible corrective measures are given in Table 3.

 

Table 3. Some common failures and remedies

Problem

Typical Causes

Possible Corrections

Flange leaks

 

Poor piping flexibility

Improve piping flexibility.

Poor gasket compression

Ensure flanges, nuts and bolts meet gasket requirements. Ref. ASME B31.3 code

Poor flange alignment

Correct alignment. Ref. ASME B31.3 code.

Ensure adequate piping supports are provided.

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