Capital Spares: The SPIR Is Where the Leverage Is Lost

On a capital project, the spare parts order is almost always the last commercial act. The main equipment has been awarded, the vendor has been mobilised, the drawings are in approval, and somewhere in the vendor document register sits a Spare Parts Interchangeability Record waiting to be returned. By the time it comes back priced, the buyer has no leverage left. The competitive tension that existed during bid evaluation has been discharged. The vendor is now a sole source for parts that will be consumed for the next twenty five years, and both parties understand that.

This is not a marginal line item. On a typical process plant, commissioning and two-year operating spares run between four and eight percent of equipment capital value, and the parts bought in that single transaction set the price basis for decades of subsequent replenishment. A pressure gauge quoted at many times its open market price on a post-award spares list is not an anomaly. It is the predictable output of a process that priced the equipment competitively and the parts afterwards.

A commercial document filed as a technical one

The SPIR exists to do one thing: identify every replaceable part in a supplied item, state whether it is proprietary or commercially available, give its original manufacturer and part number, its expected consumption rate, and its price. In practice it is treated as a maintenance deliverable. It routes to the reliability engineer, who assesses criticality, and to the materials group, who set up stock codes. Almost nobody treats it as a price schedule, which is exactly what it is.

The distinction matters because of where the money actually sits. A centrifugal pump package contains perhaps two hundred distinguishable components. Fifteen or so are genuinely proprietary: the impeller, the casing wear rings, an OEM-design seal cartridge, the shaft. The rest are bearings, seals, gaskets, fasteners, instruments and couplings manufactured by third parties and available under their own part numbers at a fraction of the packager's price. Whether the buyer can ever access those numbers depends entirely on whether the SPIR required original manufacturer identification, and on whether anyone checked that the returned document actually provided it.

Most returned SPIRs do not. They carry the packager's internal part number and leave the original manufacturer field blank, or populate it with the packager's own name. That single omission converts a catalogue bearing into a sole-source item for the operating life of the asset. It is rarely deliberate concealment. It is what happens when the form is completed by a proposals engineer under schedule pressure and reviewed by someone checking that the boxes are filled rather than what is in them.

The four failures that repeat

Sequencing. Spares are priced after award because the bid evaluation was structured around equipment price and delivery. Any enquiry that does not require a priced, completed SPIR as part of the technical bid has already decided that spares will be bought without competition. The correction is not complicated. Make the SPIR a mandatory returnable, and carry the total of commissioning and two-year operating spares into the evaluated bid price. Bidders price parts differently when the parts number affects whether they win.

Quantity method. Two-year operating spares are conventionally sized from the vendor's recommended consumption rate, which is an estimate produced by the party selling the parts. It is not adjusted for actual duty, for the number of identical units on the site, or for the fact that a plant running six identical pumps does not need six complete sets of everything. Commonality analysis across the full equipment list routinely removes a fifth to a third of a recommended holding without reducing coverage. It can only be done if the SPIRs are comparable, which means issuing them on a common template and requiring them back in structured form rather than as scanned PDFs.

Interchangeability. This is the word in the document title and the thing least often verified. Interchangeability is a claim that a part fits and functions in more than one position, and it is only useful if it survives the vendor's own revision practice. Equipment suppliers change component sources between serial numbers without notifying the buyer, because the change is invisible at the equipment level. A spare bought against serial number 001 may not fit serial number 004 of what the purchase order calls the same machine. The protection is a contractual obligation to notify the buyer of any bill of materials change during the warranty and spares supply period, together with the right to updated documentation at no cost. Very few purchase orders contain it.

Obsolescence timing. The parts most likely to become unavailable are not the mechanical ones. They are the electronic ones: control cards, operator panels, drive modules, transmitters with embedded firmware. These carry commercial lifecycles of seven to ten years against plant lives of twenty five or more. A spares strategy that buys mechanical parts deeply and electronic parts thinly has the risk profile precisely inverted, because a casting can be re-manufactured from a drawing and a discontinued control card cannot.

How we handle it

We treat the SPIR as a bid document with the same status as the technical datasheet, and we issue it with the enquiry rather than after award. The template requires the original equipment manufacturer name and part number for every line, plus a positive statement of whether each item is proprietary. A line returned without that information is an incomplete bid, not a document to be chased during expediting.

We evaluate the spares total inside the bid comparison rather than alongside it. A supplier who is two percent cheaper on the machine and forty percent more expensive on the parts is not the low bidder, and the tabulation should say so before the recommendation is written. Where parts pricing sits materially out of line with equipment pricing, that is itself qualification information: it tells you where the supplier intends to earn its margin, and over what period.

Then we verify. Third party items identified on the SPIR are checked against their actual manufacturers, and where a bearing, seal or instrument turns out to be a standard catalogue item, we say so in the evaluation and price it independently. None of this is exotic work. It is ordinary sourcing discipline. But it has to happen before the order is placed, because afterwards the buyer is negotiating with the only party who knows what is inside the machine.

The window closes at award

Every commercial term governing spare parts supply for the next two decades is set in the weeks before a purchase order is signed, and almost none of it is set by the price on the equipment quotation. The buyer who requires a complete, priced, manufacturer-identified SPIR as a condition of bid, and who then evaluates it, pays a market price for parts. The buyer who accepts it as a post-award deliverable pays whatever a sole source decides, for as long as the asset runs.

If your current enquiry template treats the SPIR as an attachment rather than a priced returnable, that is the single change worth making before the next package goes out.