A turnaround has a fixed start date and a fixed end date, and every item inside that window is on a critical path whether or not anyone drew it that way. A control valve arriving two days late is not a late delivery. It is a delayed restart, and it is measured in lost production per day rather than in procurement performance.
What is striking, having run this kind of supply repeatedly, is how rarely the failure sits in manufacturing. Manufacturers generally hit their quoted dates. The schedule breaks somewhere else, and almost always in a detail that cost nothing to verify at order stage.
The five failures that actually occur
1. Face-to-face dimension
A valve correct in body material, trim, rating and actuator, but wrong in face-to-face dimension, is an unusable valve. There is no site workaround inside a turnaround window. This is the single most common cause of a valve being returned, and it is checked in thirty seconds against the data sheet before the order is placed.
2. Positioners shipped unconfigured
Configuration is not difficult, but it is time, and it is time on the critical path with an instrument technician who has forty other items to get through. Ask for positioners configured and bench-tested against the data sheet before shipment. Most manufacturers will do it if asked at order stage and will not if asked afterwards.
3. Failure action assumed rather than stated
Fail-open, fail-closed or fail-in-place is a process safety decision documented on the data sheet. When the enquiry carries only a tag number, that decision is made by whoever assembles the actuator, which is not where it should be made. Correcting it at site means changing the spring and re-benching.
4. Certification arriving after the equipment
Material certificates and pressure test records that arrive three weeks after the valve will hold up a handover that is otherwise complete. Documentation should be a shipment condition rather than a follow-up action.
5. One pallet, forty items, no sequence
Valves arriving as an undifferentiated consignment have to be identified and sorted under time pressure, at the moment the site has the least capacity for it. Consolidation and tagging by unit area, in installation sequence, costs the supplier very little and saves a genuinely useful amount of site time.
Reading a quoted lead time properly
Lead time quotations in this sector are rarely wrong, but they are frequently misread, because a quoted figure usually covers manufacturing and nothing else.
- Drawing approval — if the order requires certified drawings before manufacture, the clock does not start until they come back approved. Two weeks disappear here routinely.
- Actuator supply — often a separate manufacturer with a separate lead time. The package date is the later of the two, not the valve date.
- Third party inspection — inspector availability is scheduled, and scheduling it after the goods are ready adds a week.
- Documentation compilation — a real activity with real duration on engineered equipment.
- Transport and customs — the difference between ex-works and delivered can be three weeks on a sea shipment, and it is your three weeks.
The practical habit is to ask for a delivered-to-site date with these stages itemised, rather than a manufacturing lead time. A supplier who cannot break it down that way probably has not thought about it.
Working backwards from the window
The sequence below is what we use on turnaround packages, and it is deliberately front-loaded. Everything that can be verified before an order is placed costs a few days of engineering attention. Everything discovered afterwards costs schedule.
- Fix the date you need items on site — not the date you want to order. Work backwards from there.
- Complete the data sheets first. Incomplete data sheets are the most common cause of a late start, because manufacturers will not price properly against them.
- Verify before placement. Dimensions, trim, actuator sizing, failure action, certification requirement, area classification. Checked line by line.
- Agree documentation as a shipment condition. Stated in the order, not requested later.
- Consolidate and tag by unit area. In installation sequence.
- Report status against the turnaround schedule — not against the purchase order. A slipped item matters only in relation to the window it has to fit into.
The item that is easiest to get wrong
If you take one thing from this: check face-to-face dimensions against the existing installation before you order, particularly where the valve being replaced is not the same brand as the one being fitted. It is the cheapest check in the entire process and the most expensive omission.
If you have a turnaround coming up, send us the valve and instrument list with the data sheets. We will come back with delivered-to-site dates against your window and flag the items that will not make it before you have committed to a schedule that depends on them.