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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The most common HTF-related injury is thermal burns. Whenever possible the system should be allowed to cool sufficiently to prevent burns from hot fluids or equipment contact when hands-on work begins. An additional benefit of cooling the fluids is reduced vapor pressure, thereby lowering potential exposure to fluid vapors.

Should non-routine material transfers be required, selection of hose materials, gaskets, containers, and O-rings/seals should all conform to manufacturer guidelines to avoid unexpected leaks, releases and physical contact. Ideally, job plans will incorporate these considerations, plus knowledge from industrial hygiene monitoring, to best determine the right combination of splash, face, eye, thermal burn, and/or respiratory protection required for each situation.

Exposure to the environment can also be safely managed by proper planning. Chemicals should be responsibly handled, but certain fluids might have regulatory restrictions that place stricter emphasis on environmental protection. This information should be provided in the MSDS.

During repairs, the bulk of the fluid should be kept properly isolated within the system designed for its containment, if possible. Any fluids that require removal by pumping, draining, blowing or other means should be transferred using equipment and materials fully compatible with the fluid chemistry. Any doubts about materials compatibility should be first resolved through discussion with a competent person knowledgeable of the fluid.

Additional preventive measures to protect the environment might include temporary dikes/curbs, drain plugs and absorbent media/pigs/socks. For fluids with high crystallizing points (e.g., DP/DPO), ensure that the piping is cleared of standing liquid to avoid possible failures due to expansion effects upon freezing. This can be done by draining low points, blowing lines with inert gas, and carefully opening low point flanges, if necessary. Successful management of this component of the job will help prevent unnecessary clean-up work, disposal of fluid and recovery materials, and allow faster completion of the job, thereby minimizing downtime.

Opportunities for reducing risks of fire, and risks to people and the environment are summarized in Table 2.

 

Table 2. Ways to reduce risk

Fire

Human exposure

Environment

Clean oily residues from area.

Cool to < 140°F.

Provide for containment.

Proper preparation for hot work.

Don’t reuse gaskets.

Keep fluid in the system.

Complete isolation of work area from process.

Ensure drain containers are water-free.

Provide for proper reuse or disposal.

Remove saturated insulation from area.

Consult with MSDS about PPE.

Consult MSDS for handling and disposal guidance.

Ensure fire watch, extinguisher and water hose are present.

Practice good industrial hygiene.

Be aware of reportable

quantities.

Retest for safe conditions after break periods in work.

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