What a technical deviation list is, from the manufacturer's side
Most explanations of deviation lists are written for the EPC evaluator who reads them. This guide is for the people who write them: the bid engineer, proposal engineer or project manager who has a requisition, a project specification, an owner standard, several addenda and a datasheet, and has to say exactly where the offer does not match.
The list is not paperwork. Some owners decide whether a bid is scored at all from it. BHEL valve tenders, for example, reserve the right to accept or reject any quoted deviation, ignore deviations that appear only in the priced copy, and use fixed columns for spec reference, description, reason and cost of withdrawal (BHEL corrigendum). Some BHEL ball- and check-valve tenders are declared "no deviation" tenders, where nothing can be added after submission (BHEL tender).
On the buyer's side, the evaluator checks each quote against the correct requisition issue and its reference documents, and produces clarification requests, a list of unacceptable deviations and a technical bid comparison (Red Bag CM-PE-510). Your list is the input to that process. See technical bid evaluation for what happens next.
The seven columns and what goes in each
| Column | What to write | Common mistake |
|---|---|---|
| Spec clause | Document number, revision and clause, for example "PS-VAL-001 Rev 2, §4.2". One clause per row. | Citing a whole section, or the wrong revision after an addendum. |
| Requirement | The requirement in short, in your own words, with the key value (material, rating, test, certificate). | Pasting a whole paragraph, so the evaluator cannot see the point at issue. |
| Offered | What you actually offer, with the same units and the datasheet reference. | Writing "as per our standard" with no value. |
| Status | One of: Complies, Clarification, Deviation, Not offered. See the status table below. | Mixing statuses, such as "complies with deviation". |
| Deviation / clarification | The exact difference, stated once, in one or two sentences. | Restating the requirement instead of the difference. |
| Justification | Why the offer is technically acceptable: equivalence, service conditions, qualification evidence, attached certificate. | Commercial reasons only ("our standard design"). |
| Cost of withdrawal | Price and lead-time impact if the buyer rejects the deviation and you must comply, or "no cost". | Leaving it blank, which forces a clarification round. |
If the tender supplies its own deviation form, use the tender's form and its column order. Map these seven fields onto it rather than attaching a second table.
Status values: use four, and define them
| Status | Meaning | When to use it |
|---|---|---|
| Complies | The offer meets the requirement as written. | Only when you can point to the datasheet or certificate that shows it. |
| Clarification | The offer meets the intent, but wording, reference or method differs, or the requirement is ambiguous. | An equivalent test standard, a conflicting clause, a missing value in the spec. |
| Deviation | The offer does not meet the requirement as written. | Different material, rating, test, certificate type or scope. |
| Not offered | The item is excluded from the scope of supply. | Spares, site services or documents you are not quoting. |
Some tenders ask for a full compliance statement (every clause, including those you comply with) and a separate deviation list (only the exceptions). The first is a compliance matrix. The deviation list carries only the rows that are not "Complies".
Worked example: 6-inch Class 600 trunnion ball valve
The example below uses an invented project specification (PS-VAL-001) for a 6-inch, ASME Class 600, full-bore trunnion-mounted ball valve. Every value is illustrative. It shows how one row should read, not what any real specification requires.
| Spec clause | Requirement | Offered | Status | Deviation / clarification | Justification | Cost of withdrawal |
|---|---|---|---|---|---|---|
| PS-VAL-001 §4.2 | Body and closures forged ASTM A350 LF2 Cl.1 | Cast ASTM A352 LCC body, forged A350 LF2 closures | Deviation | Cast body offered instead of forged. | ASTM A352 covers steel castings for pressure-containing parts in low-temperature service, and grade LCC has a usual minimum test temperature of −46 °C, which covers the design minimum temperature in the datasheet (ASTM A352). Casting inspection levels are listed in the datasheet. | Forged body available: +9% unit price, +5 weeks. |
| PS-VAL-001 §4.5 | Seat inserts PEEK | Reinforced PTFE seat inserts | Deviation | Seat insert material differs. | Design temperature in the datasheet is within the RPTFE rating; PEEK is offered as an option. | PEEK seats: no price change, +2 weeks. |
| PS-VAL-001 §5.1 | Fire tested to API 607 | API 607 fire-type test certificate from an earlier edition, for this valve family | Clarification | Qualification is to an earlier edition of the fire-test standard. | The design has not changed since the qualification test. Buyer to confirm the earlier-edition certificate is acceptable. | New API 607 qualification: not offered within the bid lead time. |
| PS-VAL-001 §6.3 | Stem seal qualified to ISO 15848-1, class BH, CO1 | Type test report to ISO 15848-1 class BH, CO1 on a qualified stem seal of the same design family | Clarification | Qualification is by family, not on this exact size. | Buyer to confirm that the family qualification covers this size; report reference listed in the datasheet. | Size-specific test: +USD 14,000 one-off, +6 weeks. |
| PS-VAL-001 §7.2 | EN 10204 type 3.2 certificates for pressure-containing parts | EN 10204 type 3.1 certificates | Deviation | 3.1 offered instead of 3.2. | Material is tested by our authorised inspection department; 3.2 needs the buyer's or a third-party inspector's validation. See EN 10204 3.1 vs 3.2. | 3.2 certificates: +3% and +2 weeks, inspector fees by buyer. |
| PS-VAL-001 §9.4 | Pressure testing to API 598 | Pressure testing to API 6D | Clarification | Valve tested to its product standard rather than API 598. | API 6D, the governing product standard in §3.1, has its own shell and seat test requirements. Buyer to confirm API 6D testing is acceptable. | Additional API 598 test: no cost, +1 week. |
| PS-VAL-001 §11.1 | Two-year operating spares | Commissioning spares only | Not offered | Two-year spares excluded from this price. | Quoted separately on request so the base price stays comparable. | Two-year spares: priced separately. |
Read the example row by row
Each row names one clause, states the offer in the same terms as the requirement, gives one status, says what differs, gives a technical reason and prices the alternative. An evaluator can accept or reject each row without calling you.
Deviation, clarification, exception and TQ: the differences
| Term | Who raises it | When | What it means |
|---|---|---|---|
| Deviation | Manufacturer | In the offer | The offer does not meet a requirement as written. |
| Clarification | Manufacturer | In the offer | The offer meets the intent, but a reference, method or wording differs, or the spec is unclear. |
| Exception / exclusion | Manufacturer | In the offer | Scope not supplied. Often listed as "Not offered". |
| Technical query (TQ) | Either side | Before or during evaluation | A question that needs a written answer before the offer can be completed or evaluated. See technical query. |
How to build a deviation list in seven steps
- Collect every governing document: requisition, project specification, owner standards, datasheets, addenda and the tender's own deviation form. Note each revision.
- Decide which document wins when two disagree. Most requisitions state an order of precedence; if not, raise a TQ. See governing-document precedence.
- Go clause by clause through the specification and datasheet. Record each requirement with its value, even where you comply, so nothing is missed.
- Compare each requirement with your datasheet, catalogue and past qualification records, and set one status.
- For every row that is not "Complies", write the difference once, a technical justification and the cost of withdrawal.
- Have a second engineer check the non-compliant rows and every row that cites a test, certificate or material.
- Copy the final rows into the tender's form, check that the priced and unpriced copies match, and submit.
Step 3 is where most of the time goes and where most misses happen. A free deviation list template and compliance matrix gives you the columns ready to fill.
Mistakes that make a bid non-responsive
- Leaving a deviation off the list. Many tenders hold you to full compliance for anything not declared.
- Declaring a deviation in the priced copy only. BHEL, for one, ignores deviations that are not in the unpriced technical copy (BHEL corrigendum).
- Missing a mandatory document. A missing API 6D certificate or manufacturer authorisation letter is a typical rejection ground in OGDCL evaluations, where a zero in any key sub-category makes the bid non-responsive even if the total clears the 70-point pass mark (OGDCL clarification; OGDCL evaluation report).
- Citing the wrong revision after an addendum.
- Commercial justifications for technical deviations.
- No cost of withdrawal, which forces a clarification round and can push the bid down the evaluation queue.
Where OdysseyGPT fits, and where it does not
OdysseyGPT reads the whole specification package, checks each customer requirement against your own datasheets and standard specifications, and gives it a status (complies, deviates, clarification, not addressed, document requested, not applicable or out of scope) with a quote from the source page, sheet or cell. It exports an editable compliance matrix and a deviations & clarifications list. A bid engineer, proposal engineer or project manager then decides every open item and writes the justification and cost of withdrawal. It is built for manufacturers of engineered equipment; see OdysseyGPT for manufacturing.
Its limits matter. It does not interpret engineering drawings such as general arrangements or P&IDs, it does not send anything to the customer, and it cannot know an owner's unwritten preferences. Your engineers decide every open item and own what goes out.