Two public tenders for the same plow edge, issued the same month: one produced four bids within a narrow band that the evaluation could score, and the other produced four prices spread so widely that the technical panel could not tell whether they described the same product. Nothing about the edges differed. The difference was whether the specification named measurable properties or described the edge in adjectives.
This is a clause-by-clause walkthrough for the buyer writing that document. It sets out what each clause has to establish, what a supplier can actually be held to at delivery, and how the evaluation criteria can be written so that the cheapest bid is not automatically the one that wins on paper.
What a tender specification has to survive
A specification has three audiences and has to work for all of them. The bidder reads it to decide what to quote and what to exclude. The evaluator reads it to score competing offers on one basis. The storekeeper reads it months later to decide whether a delivery matches what was ordered.
Most weak specifications are written for the first audience only, describing the product well enough for a supplier to price it and leaving the other two with nothing operational. The test worth applying before publication is simple: can a receiving inspector, with the document in hand and no other information, decide whether a delivered lot conforms? Where the answer is no, the clause needs a value, a tolerance or a document attached to it.
Carbide insert specification: grade and hardness clauses
Name the properties and methods, not a supplier’s code.
The grade clause should require four reported values rather than a designation: the grain size class with the method used to measure it, the binder content, the hardness on the HRA scale, and the transverse rupture strength with the standard it was measured to.
Naming a brand grade restricts competition and does not achieve the objective, because the performance is what the tender is buying, and measurable properties can be compared between suppliers while a code cannot.
The clause also has to say what happens to the values after award. A grade declaration that applies only to the quotation is worth very little, so the tender should require the same four values to be reported with each delivered lot, tied to the batch reference. Equipment standards that constrain the assemblies these inserts go into are maintained by SAE International, and the test methods behind the values by ASTM International.
Geometry and tolerance clauses
Geometry is where a loose specification costs the most, because a dimensional deviation that is invisible on a bench becomes a fitment problem across a whole blade. Three items belong in the clause. The insert profile and its nominal dimensions, stated so they can be measured. The dimensions that locate the insert in its seat, with tolerances. And the drawing revision the supply is to be produced to, which the bidder is required to quote back in the offer.
The tolerance element needs one more paragraph than it usually gets, because a tolerance without a stated measurement method is not enforceable. Requiring the method to be named, along with the resolution of the instrument used, means that a disputed lot can be settled by re-measuring rather than by correspondence. Which dimensions carry the tightest tolerances, and why, is set out on the dimensional tolerance page.
Retention and bond verification
Where inserts are bonded into the edge, the bond is part of the product being purchased and belongs in the specification. The clause should name the retention method, the filler or fixing specification, and the inspection that will be applied to the joint before dispatch. A tender that specifies the insert and leaves the joint to the supplier is buying half a component.
The verification element is what makes the clause enforceable. Requiring a joint inspection with named acceptance criteria gives the receiving inspection something objective to check and gives the supplier a defined standard to work to. Brazing practice and the vocabulary for describing joint imperfections are published by the American Welding Society, which is a useful reference for writing the criteria without inventing a private standard.
Testing and sampling requirements
The sampling clause tells a bidder what will be checked and tells the evaluator what the supplier has agreed to. The sequence below is written so that it can be lifted into a tender and then used at goods-in without rewriting.
- State which dimensions are measured on every lot and which are sampled, rather than requiring everything to be measured.
- State how samples are drawn, in terms that a storekeeper can apply without interpretation.
- State the measurement method and instrument resolution for each measured dimension.
- State where destructive or laboratory testing may be required, and who carries the cost when a lot fails.
- State the response expected from the supplier when a lot is rejected on measurement.
The fourth item is the one that removes most of the argument from a failed delivery. Where the tender is silent, the cost of testing a disputed lot becomes a separate negotiation, and the practical outcome is that testing does not happen and the lot is used with reservations.
Documentation and traceability
Traceability clauses are cheap to write and expensive to discover missing, so the tender should name the records that travel with the supply rather than asking for documentation in general terms.
- The batch reference that links a delivered lot to its production record.
- The drawing revision the lot was produced to.
- The dimensional record for the dimensions named in the sampling clause.
- The grade declaration for the lot, carrying the four values named in the grade clause.
- The joint inspection record, where retention is part of the specification.
The third item is the one that distinguishes a supplier who measures from one who inspects. A pass or fail statement satisfies a checklist; a recorded set of values against a named drawing revision is what supports a comparison across two seasons and two suppliers.
Acceptance criteria
Acceptance criteria turn a specification into a decision, and they need to say what happens rather than only what is required. Three outcomes should be defined for each measured requirement: conforming, non-conforming but usable with a concession, and rejected.
The middle category is the one most tenders omit, and it is the one that gets used. In practice a lot will sometimes arrive with a deviation that does not affect function, and without a defined concession route the choice is between rejecting a usable delivery and accepting one informally. Writing the route into the tender keeps that decision documented and keeps the requirement meaningful for the deviations that do matter.
Evaluation scoring that avoids lowest-price traps
Evaluation criteria are where the specification is either defended or quietly abandoned, because a technically precise document scored purely on price produces the lightest compliant offer. The table below sets out criteria that separate bids on something other than the number.
| Criterion | What it tests | Why it belongs |
|---|---|---|
| Completeness of the technical response | Whether every named property was reported with its method | An incomplete response cannot be evaluated, only accepted or rejected |
| Traceability offered per lot | Whether delivered batches can be tied to their records | Determines whether a future claim is resolvable |
| Lead time against the fleet’s season | Whether supply arrives when the work happens | A cheaper bid arriving late carries its own cost |
| Concession and rejection process | Whether the supplier has a route for deviations | Shows whether the specification will be applied at delivery |
| Price against a defined specification | The cost of the product actually being bought | Price becomes comparable once the product is fixed |
The last row is the point of the whole exercise. Price is the right final criterion once the specification has made the offers comparable, and the wrong only criterion when it has not, because the offers are then describing different products at different risk.
Building the clause set in order
The clause set is easiest to write in the order the product is made, because each clause then depends on the one before it and nothing is left implicit.
- Define the insert: profile, nominal dimensions and the drawing revision.
- Define the material: the four grade values and the methods behind them.
- Define the assembly: retention method, filler or fixing specification, and joint inspection.
- Define the verification: sampling, measurement methods and the concession route.
- Define the records: what travels with each lot and what it has to contain.
- Define the evaluation: how the responses will be scored and what a compliant bid has to contain.
Written in this order, the specification can be checked against itself: every requirement in the verification clause should trace back to something defined earlier, and anything that cannot be traced is usually a requirement that cannot be enforced. Drawing conventions for stating these requirements are published by ASME, and the general principles of specification by ISO. The receiving checks that apply the clauses at delivery are set out on the delivery inspection page.
SENTHAI manufactures tungsten carbide inserts and plow edges in Rayong, Thailand, supplies distributors and public fleets against specified drawings, and issues each lot with the batch reference and dimensional record that a tender of this kind requires. What the documentation contains is described on the quality control page, and tenders that need the documentation set confirmed before submission can be discussed through the contact page.
FAQ
Should a tender specify a brand of carbide grade?
Specifying a brand restricts competition and usually fails its own objective, because the point is the performance, not the supplier’s code. Naming the measurable properties instead, with the test methods, allows equivalent grades to bid while giving the evaluation something objective to score.
Isn’t lowest price the simplest award criterion?
It is the simplest to write and the hardest to live with, because two low bids can describe two different products. Where the specification is loose, the lowest bid tends to be the lightest compliant interpretation of it, and the difference is discovered during the season rather than at the evaluation.
How do you verify a grade at delivery without a laboratory?
You verify identity rather than chemistry. What can be checked at goods-in is that the marking matches the order, that the batch reference ties the lot to its production record, and that the documentation specified in the tender arrived with it. Destructive or laboratory testing is normally reserved for a disputed lot.
What happens if a supplier offers an equivalent product?
The tender should say in advance. Where equivalents are allowed, the specification has to state which properties must be reported for the equivalence to be assessed, and on which basis the comparison will be made. Without that clause, equivalence becomes a negotiation rather than an evaluation.
Send the drawing revision, the quantities and the records your tender has to name. The SENTHAI engineering desk will confirm the grade values, tolerances and documentation that can be issued with each lot.
This article is one step in the Snow Plow Blade Selection Guide, which works the whole decision in order — surface, position, size, geometry and material — through to the written specification.