How to Compare Ball Valve Quotations with Different Technical Deviations | TBE, Exclusions, Lifecycle Risk

Reject These Bids Before Price Comparison

A quotation should not enter the final price ranking while any of the following items remains noncompliant:

• Allowable pressure is below the design pressure at the stated design temperature.
• Body, trim, seat, seal, packing, or bolting materials are unsuitable for the fluid.
• The minimum bore cannot pass the required cleaning pig or inspection tool.
• The valve cannot safely relieve trapped body-cavity pressure.
• Flanges, weld ends, face-to-face dimensions, or pipe bore do not match the piping.
• The actuator cannot operate the valve at maximum differential pressure.
• The actuator can apply more torque than the stem or drive train can safely carry.
• Mandatory fire-safe, fugitive-emission, sour-service, or low-temperature evidence does not cover the offered valve.
• The supplier will not identify the actual manufacturing and testing factory.

Missing evidence is not the same as a confirmed deviation. Mark it as an open clarification until the supplier provides the drawing, certificate, calculation, material list, or test plan needed to make a decision.

Use These Columns in the TBE

Use one row for every requirement that can change safety, performance, installation, testing, documents, delivery, or cost.

Do not calculate one overall compliance percentage. A quotation that meets 39 of 40 requirements can still be unacceptable if the missing requirement is pressure rating, cavity relief, material compatibility, or emergency operation.

Record document conflicts as open items. If the quotation states PEEK, the data sheet states reinforced PTFE, and the drawing states “vendor standard,” the seat material is not confirmed.

Verify the Standard, Edition, and Licensed Factory

Write the exact standard edition and applicable addenda in the TBE. API identifies API Specification 6D, 25th Edition, November 2021, with Addendum 3 issued in March 2025 and an API Monogram Program effective date of September 5, 2025.^[1]

“Designed to API 6D” does not prove that the supplied valve will carry an API Monogram. Check the legal manufacturer, factory address, product scope, and current licence status in the API Composite List.^[2] API describes the Monogram Program as a licensing system that permits licensed manufacturers to apply the mark to products made under the applicable programme requirements.^[3]

The factory named in the certificate should match the factory that performs assembly, pressure testing, marking, and release. The practical checks for licence scope and serial-number records are also covered in the API 6D ball valve manufacturing guide.

ASME B16.34 covers pressure-temperature ratings, materials, dimensions, tolerances, nondestructive examination, testing, and marking for applicable valve construction.^[4] It does not by itself confirm the correct seat, seal, bore, actuator, cavity-relief arrangement, fluid compatibility, or project-specific testing.

When a supplier offers an “equivalent” standard, require a table showing each different clause and its effect. A general statement of equivalence is not enough.

Confirm Pressure Rating at the Actual Temperature

Ask for the allowable pressure of the exact body material at the maximum design temperature. Do not approve a valve from the class number alone.

For an illustrative Class 600 valve offered for 100 barg at 180°C, the supplier should provide the applicable pressure-temperature rating for the stated body material. The review must also cover:

• Body and closure
• Pressure-boundary bolting
• Ball and stem
• Seat inserts and seat seals
• Body gaskets and O-rings
• Stem packing
• Gearbox lubricant
• Actuator, solenoid, switches, tubing, and controls

If the body is suitable for 180°C but the offered soft seat has a stated continuous limit of 150°C, the complete valve is not suitable for the design condition.

Check the valve against normal operation and every credible temporary condition:

• Maximum closing differential pressure
• Steam cleaning or hot flushing
• Cold start and minimum ambient temperature
• Rapid gas depressurization
• Vacuum
• Thermal cycling
• Emergency shutdown
• Long periods without movement

Where liquid can be trapped in the valve cavity, API 6D Addendum 3 requires automatic cavity relief. For temperatures up to 121°C, the addendum limits cavity-relief pressure to no more than 33% differential pressure above the valve pressure rating.^[1]

Require the supplier to show:

• Whether liquid can be trapped in the open or closed position
• Which seat or device relieves pressure
• The direction of relief
• The relief-pressure basis
• Any external relief valve, line, or discharge connection
• The test used to confirm the function

Measure the Smallest Bore and Map the Seat Pressure Path

The smallest opening through the ball, seats, body, end connectors, welds, gaskets, and internal parts controls the real flow path.

For an illustrative DN 300 valve:

• A 276 mm bore has an area of about 59,800 mm².
• A 250 mm bore has an area of about 49,100 mm².
• The 26 mm diameter reduction cuts the flow area by approximately 18%.

Both valves may still be labelled DN 300, but they do not provide the same flow area or pig passage.

Require the supplier to provide:

• Ball-port diameter
• Seat opening
• Body and end-connector bore
• Weld-end inside diameter
• Internal steps and transitions
• Connected pipe schedule
• Maximum stem or ball intrusion when fully open
• Approved pig or inspection-tool dimensions

The full-bore and pigging guide shows why the nominal valve size alone cannot confirm pig passage.

For a trunnion valve, require a sectional drawing that shows the pressure path through both seats and the body cavity.

The soft-seated trunnion valve specification provides examples of how SPE/SPE, SPE/DPE, and DPE/DPE arrangements can be stated in a quotation.

Name Every Material and Certificate

“Carbon steel body with stainless-steel trim” is not enough for technical approval.

If the contract requires EN 10204 Type 3.1 or Type 3.2 inspection documents, state the required type. Do not ask only for a general “MTR.”^[5]

Material traceability should link the specified parts to each valve serial number. In an illustrative order of 20 valves, tracing the body, closure, ball, stem, and seat rings creates at least 100 part-to-valve links. One general batch certificate does not provide the same traceability.

For H₂S-containing oil and gas production or natural-gas treatment, ISO 15156-1 gives general material-selection rules and supplements rather than replaces the applicable design code.^[6] ISO 15156-2 addresses H₂S-related cracking in carbon and low-alloy steels but does not cover general or localized corrosion loss.^[7]

A claim of “NACE compliant” should identify:

• The applicable ISO 15156 part and edition
• The actual H₂S service environment
• The parts covered
• Material grades and heat treatment
• Maximum hardness
• Welding and repair controls
• Temperature, chloride, and other environmental limits

Match Seat, Seal, Leakage, and Torque

Seat selection should be based on the actual fluid, temperature, differential pressure, solids, and operating frequency.

The term “PTFE seat” is too broad. Request virgin PTFE, modified PTFE, filled PTFE, PEEK, PCTFE, nylon, or the supplier’s exact material code.

For metal-seated valves, require:

• Ball and seat base materials
• Hardfacing or coating material
• Application process
• Minimum finished thickness
• Hardness range and hardness difference
• Surface finish
• Lapping method
• Leakage acceptance criteria
• Repair limit

The forged soft-seated floating valve and forged metal-seated floating valve pages show the different fields that should appear in soft-seat and metal-seat quotations.

Seat, leakage, and actuator sizing must be reviewed together. A harder or more tightly loaded seat may reduce leakage but increase breakaway torque.

Compare Test Quantity and Acceptance Criteria

ISO 5208:2015 covers tests used to establish pressure-boundary integrity, closure tightness, and structural adequacy of the closing mechanism. It is used with the applicable product standard.^[8]

“Tested to ISO 5208” is not a complete test scope. Each quoted test should state:

For an order of 24 valves:

• Testing every valve produces 24 test records.
• A 10% sample produces 2.4 units, normally rounded to 3 whole valves.
• A quotation covering 3 valves does not provide the same production evidence as one covering all 24.

List NDE by method, part, coverage, examination stage, acceptance criteria, personnel qualification, and repeat-examination rule. “Standard NDE” may mean visual inspection in one bid and volumetric examination in another.

The supplier’s ITP should define every acceptance criterion and required record. The valve ITP guide explains hold, witness, surveillance, and review points, while the API 6D testing guide lists common shell, seat, and functional test checks.

Match Fire and Emission Certificates to the Offered Design

ISO 10497:2022 defines fire type-testing for soft- and metal-seated isolation valves. Powered electric, pneumatic, and hydraulic actuator testing is outside its main scope.^[9]

Compare the tested valve and offered valve for:

• Manufacturer and factory
• Floating or trunnion construction
• Body and body-joint design
• Seat type
• Stem seal
• Size and pressure class
• Body material
• End connection
• Standard edition
• Qualification-extension rules

A fire test on a small floating valve does not automatically qualify a large trunnion valve with different seats, body joints, and stem seals.

ISO 15848-1:2015 covers type testing for external leakage from stem seals and body joints.^[10] Amendment 1 was issued in 2017.^[11] ISO 15848-2:2015 covers production acceptance testing.^[12]

Require the quotation to state:

• Leakage class
• Temperature class
• Endurance or cycle class
• Test fluid
• Packing and body-joint design
• Qualification range
• Production test quantity

“Low-emission packing” proves only that a packing product has been selected. It does not prove that the complete offered valve has the required qualification.

Confirm Dimensions and Actuator Capacity

ASME B16.10:2022 covers face-to-face and end-to-end dimensions for applicable valves.^[13]

Compare:

• Face-to-face or end-to-end length
• Flange facing, finish, drilling, and bolt-hole orientation
• Weld-end bore, wall thickness, transition, and bevel
• Centerline-to-top dimension
• Actuator envelope
• Valve weight and center of gravity
• Lifting and support points
• Drain, vent, and injection orientation
• Space needed to remove the actuator or service the packing

A valve that is 50 mm longer than the approved face-to-face dimension may require a new spool with two field welds. The change may also require weld NDE, coating repair, dimensional checks, support changes, and a piping stress review.

For actuator sizing, keep three numbers separate:

1. Maximum valve torque
2. Project service factor
3. Actuator output at the worst supply condition

Illustrative undersizing example:

• Maximum valve torque: 7,800 N·m
• Service factor: 1.5
• Required output: 11,700 N·m
• Available output at minimum air pressure: 11,500 N·m
• Shortfall: 200 N·m, or about 1.7%

The actuator does not meet that sizing basis.

Illustrative overtorque example:

• Valve-stem allowable torque: 16,000 N·m
• Maximum actuator output: 22,000 N·m
• Actuator output above stem limit: 6,000 N·m, or 37.5%

The actuator package needs torque switches, pressure control, mechanical limits, or another approved method that prevents damage.

ISO 5211:2026 covers part-turn actuator attachment interfaces but does not cover the attachment of the intermediate support to the valve.^[14] Check the bracket, coupling, key, fasteners, alignment, and stem strength separately. The valve torque-curve guide provides the torque fields that should appear in the actuator calculation.

Price Every Exclusion

Search the commercial quotation, technical data sheet, deviation list, drawing, ITP, document list, actuator schedule, and sales conditions. The exclusion list alone may not show everything that is missing.

For each item marked “by others,” name the party responsible for purchase, installation, interface dimensions, complete assembly testing, performance, and warranty.

Confirm the actual factory, foundry or forge, machining location, test facility, subcontracted NDE, and coating supplier before award. The ball valve factory-audit guide lists records that are more useful than a general customer list.

Calculate the Normalized Bid Price

Normalized bid price = quoted price + missing scope + required upgrades + inspection cost + installation changes + confirmed schedule cost

Record the source of every figure:

• Confirmed supplier quotation
• Budget quotation
• Previous project cost
• Construction estimate
• Provisional allowance

Do not count one exclusion twice. If the complete actuator price has already been added, apply another actuator-related cost only when a separate interface, delivery, assembly, testing, or warranty cost remains.

Add Repair, Spares, and Shutdown Cost

Lifecycle-adjusted cost = normalized bid price + expected maintenance + expected repair + expected replacement + expected shutdown cost

Use a stated study period, discount basis, and cost assumptions. NIST Handbook 135 explains life-cycle costing, present-value calculations, and uncertainty methods, although it is not a valve-specific standard.^[15]

For uncertain events:

Expected cost = probability of occurrence × financial consequence

Illustrative example:

• Seat-leak probability for Valve A: 20%
• Repair and shutdown consequence: $50,000
• Expected cost: $10,000
• Seat-leak probability for Valve B: 5%
• Expected cost with the same consequence: $2,500
• Difference between the two offers: $7,500

Use evidence from comparable service, maintenance history, manufacturer records, or an approved project risk method. Do not invent failure probabilities to change the ranking.

Include:

• Stem, seat, and body-joint leakage
• Increasing torque or valve seizure
• Body-cavity overpressure
• Coating failure and external corrosion
• Actuator and accessory failure
• Valve removal, lifting, cutting, welding, and NDE
• Process draining, purging, cleaning, or gas freeing
• Spare-parts lead time
• Product obsolescence
• Local repair and technical support

In an illustrative project, a standard packing kit may be available in 7 days while a proprietary seat assembly requires 16 weeks. If the valve cannot remain in service during that period, the seat lead time is a shutdown risk, not just a spare-parts detail.

The stem-leak and seat-leak diagnosis guide shows why external packing repair and internal seat repair can have very different shutdown requirements.

Rank the Three Bids

If full bore is mandatory for pigging and PEEK is mandatory for the service, Bid B is rejected before price normalization.

If engineering approves the reduced bore and reinforced PTFE, add Bid B’s missing scope:

Bid B normalized price = $153,000 + $49,000 = $202,000

Bid B first appeared $33,000 cheaper than Bid A. After normalization, it is $16,000 more expensive, or about 8.6% above Bid A’s price.

Bid C cannot enter the final ranking until its fire qualification is shown to cover the offered valve. If the evidence is accepted without a price change, Bid C may remain below Bid A. If the evidence is not acceptable and fire qualification is mandatory, Bid C is rejected.

Close These Questions Before Award

Confirm the allowable pressure of the offered body material at the maximum design temperature and provide the applicable pressure-temperature rating.

State the exact ball-port, seat, body, and end-connector bore dimensions and confirm passage of the specified pig or inspection tool.

Describe the seat pressure action and show how body-cavity pressure is relieved when the valve is closed and both line sides are pressurized.

Provide the exact material grade, heat treatment, hardness, and inspection-document type for each specified pressure-containing and wetted part.

State the test medium, pressure, duration, direction, leakage limit, quantity, inspection point, and required test record.

Provide the original valve torque, applied service factor, actuator output at the minimum supply condition, and valve-stem allowable torque.

Provide the fire-safe and fugitive-emission reports and identify how their qualification ranges cover the offered size, class, body design, seat, stem seal, and manufacturing factory.

Confirm that the revised quotation includes every technical and commercial exclusion and that no unstated vendor-standard exception will apply.

Do not accept “to be confirmed after order” for any item that can change design, price, delivery, installation, testing, safety, or maintenance.

The final quotation should include the revised data sheet, deviation list, price, delivery, preliminary drawing, material list, actuator calculation, ITP, certificate list, document schedule, spare-parts list, and exclusions. Attach the accepted clarification record to the purchase order and remove superseded documents.

Finally

Reject mandatory failures before comparing price. Check the pressure rating at the actual design temperature, measure the smallest bore, identify every seat and seal, confirm test quantity, and verify actuator output at the worst supply condition. In the worked example, a $153,000 bid became $202,000 after $49,000 of missing scope was added; a 276 mm to 250 mm bore change reduced flow area by about 18%; and an actuator with 11,500 N·m output failed an 11,700 N·m requirement. Record each deviation, evidence source, cost, remaining risk, and approver before issuing the order.