Are there any recommendations on maintaining 3-way valves? They are just considered isolation valves like all others at site, manually operated and having no particular preventive maintenance plan, right?

What sort of role do maintenance engineers play during a PSSR? are they on comments receiving end only and the doers only after the comments are received? We have seen cases where a stronger role was needed like identifying if correct gaskets were installed which was to be done by themselves but ...

Yes this has to include all excursions expect those which were reviewed and evaluated not to be the ones happened during the normal operation.

Yes. Reducing distillation-column operating pressure can improve fractionation, but it also changes several important operating parameters. The key reason is that lower pressure increases the relative volatility of many components, making separation easier.

Tray hydraulics can actually become more ...

Older or simpler anti-surge controllers rely on a fixed surge line programmed for a specific gas MW. If the feed becomes lighter, the actual surge line shifts to the right (higher flow required to prevent surge). The ASV might not open in time because the control system thinks the compressor is ...

The context matters here: leaks into cooling water service are insidious because the vapors accumulate beneath the distribution decks rather than dissipate — they collect in a confined space where an ignition source eventually finds them, and Amoco's Texas City incident is a documented case where a ...

if you're looking at an existing refinery/petrochemical column with old bubble-cap trays that someone wants to replace, don't approve the change merely because the bubble caps are "old technology." The existing tray hydraulics and actual operating history should be evaluated first. Sometimes the old ...

Attaching a useful document on this.

Nothing fixed by any standard.
The primary references in this case are:
IEC 61511
Requires periodic proof testing of Safety Instrumented Functions (SIFs).
States that proof test intervals shall be established based on the required SIL and reliability analysis.
Does not prescribe a fixed PST interval ...

First of all, spaded lines during startup should be identified as part of permit system. If they are spaded, there must be an active permit. Or if spade has been put for a longer period of time and remaining system is charged up, there should have been an MOC in place support with some risk ...