Refinery process valves: compound selection across hot, sour and hydrocarbon duties

1. Why refinery duty drives compound choice

Refineries run many duties inside a single plant. Hot oil, sour gas, dry fuel gas, steam and slurry lines each behave differently in a valve. A compound that seals well in one service can wash out, harden or react in another. Selection therefore starts with the duty, not with the product name.

A risk-based valve integrity study of upstream and midstream sites, published by Valve World, reported 61 per cent of failures as passing valves and 28 per cent as seized. Distributions vary by population. Even so, the split matters for compound planning: passing valves call for sealant, seized valves call for cleaner first.

The order also matters when both symptoms appear together. A valve that is stiff and passing usually needs cleaner, then lubricant, then sealant. Skipping the cleaner wastes new sealant on dirty seats.

2. Selecting cleaner, lubricant and sealant by duty

The compound follows the duty and the media inside it. A workable order of selection is:

1. Hot hydrocarbon duty. The compound must hold its body at temperature and resist washing by the media. A non-hardening sealant suits seat sealing where heat thins ordinary lubricants.
2. Sour duty. The compound must tolerate sulphur-bearing media without breaking down or attacking valve materials. The media match matters more than sealing force.
3. Dry gas duty. Organic sealants can harden in dry gas and can seize a valve. Choose a compound rated for dry service.
4. Steam and utility duty. Water resistance and easy re-lubrication come first, because these valves cycle often.

For comparing compound families in general, start with the valve sealant buying guide. Where the gas itself drives corrosion and deposits, read about gas composition effects on valve seals.

3. Compatibility checks before choosing a compound

Before selecting any compound, confirm the job itself is possible. The gates come first:

1. The valve has injection fittings in good condition.
2. The valve design and the service suit injection.
3. Site rules and the permit-to-work allow the job.

In-service treatment is not universally possible, and some designs or sites rule it out. Where OEM documentation exists, consult it for limits and warranty terms. Valves built with injection points are designed to be maintained in service.

Then check the chemistry. Confirm the compound suits the media, the elastomers and any old product already in the valve. Hardened residue should be softened with cleaner before new sealant goes in. A new compound meeting incompatible residue can fail early. Injection stays controlled throughout: small amounts within equipment and fitting ratings, watching the pressure response, with stop-work if the response is abnormal.

4. Turnaround timing and in-service treatment

Turnarounds compress valve work into a short and costly window. Some jobs belong there: valves without fittings, internal repairs, and valves that must be removed. Many seat and stem problems do not need to wait.

Cleaning and sealing before a turnaround shortens the list of valves opened during the stop. It also gives time to order the right compounds for each duty. A condition survey ahead of planning shows which valves suit in-service treatment. Our field teams travel worldwide from India and support turnaround programmes.

Timing also affects the compound itself. A sealant injected weeks before a stop must survive the waiting period at duty temperature. Ask how long the product can wait, and request the guide for the duty in question. Cycle valves on a regular schedule, because idle valves tend to seize.

5. Proving the seal under agreed conditions

Screening evidence is not proof. Pressure rise, flow indication, sound and bubbles on a vent all suggest a passing valve; none of them confirms it. The confirming step is a seat-leak test under agreed conditions.

Field options include pressure decay across the closed valve, double block and bleed monitoring, or a witnessed leak test. Agree the method and the acceptance level in writing before work starts. API 598 and ISO 5208 are factory acceptance references, not field results. ISO 15848 similarly type tests new valves for fugitive emissions.

Know the endpoint. If a valve still passes after cleaning and controlled sealing, the honest answer is a proper assessment, or replacement. Compound selection cannot repair mechanical damage. We make non-hardening valve sealants in-house, but no compound replaces worn metal.