The three things valve makers most often conflate are the manufacturing licence, type testing and routine factory testing. All three are called “certification” or “inspection”, yet their legal nature, samples, test items and frequency are entirely different: the licence assesses the plant, type testing verifies that a particular model design is safe, and factory testing proves that a given batch can be released. Treat them as one thing and the usual outcome is a bench configured for factory testing that cannot run the full type-test programme — or, in the other direction, every unit tested to type-test scope at several times the cost, with nobody accepting the result.
This article deals only with type testing, under TSG D7002-2023 Pressure Piping Components Type Test Regulation (issued 2023-07-07, effective 2023-10-01, replacing the 2006 edition). It walks the chain: which annex applies → the 18 items → how many samples → what the certificate covers → pressure and hold times → how the certificate is renewed. Figures follow the official text; the tables are for quick orientation during planning and bench specification.
1. Separate the three: licence, type test, factory test
| Item | Manufacturing licence (TSG 07-2019) | Type test (TSG D7002-2023) | Factory test |
|---|---|---|---|
| Subject | The manufacturing company | The model / size range of a product | Every unit or every batch |
| Basis | Licensing rules for special equipment production | TSG D7002-2023 and its Annex E | Product standard + in-house inspection spec |
| Performed by | Market regulator’s audit team | An approved type-test agency | The manufacturer |
| Output | Manufacturing licence | Type-test report + certificate (4 years) | Inspection record / certificate of conformity |
| Frequency | First application, renewal | New model, design or process change, expiry | Per unit / per batch |
Three points that are easy to get wrong:
- Type testing is not a precondition for the manufacturing licence, but for products within scope, no certificate means no shipment and no use in China;
- Imported components are covered too. Valves made abroad for use in China follow the same regulation;
- Type testing does not replace factory testing. It certifies the design of a model; every unit still needs shell and seat tests to the product standard.
2. The first step is choosing the annex, not filling the form
Pressure piping valves carry component code 7320. The same valve can fall under different annexes with completely different items and criteria — picking the wrong annex is one of the most common reasons an application is returned.
| Annex | Scope | Typical products |
|---|---|---|
| E1 General valves | General-purpose valve types | Gate, globe, throttling, check, ball, butterfly, diaphragm, plug, piston, solenoid, blowdown, plugging and disc valves (13 types) |
| E2 Control valves | Control and pressure-reducing valves | Pneumatic/electric control valves, self-operated regulators |
| E3 Cryogenic valves | Design temperature below -46 °C | LNG, air separation, liquid nitrogen service |
| E4 Wellhead valves | Wellhead and choke manifold valves | Christmas tree valves, chokes, plug valves |
| E5 Non-metallic valves | Non-metallic body valves | Plastic and lined valves assessed as non-metallic |
Note the temperature boundary of E1: the applicable temperature range is set by the sample, and the design temperature must be not lower than -46 °C. Below that line the valve belongs in E3; an E1 certificate cannot be stretched to cover cryogenic service.
3. The 18 items of E1: 7 document checks, 11 physical checks
Technical document review (7)
- Design conditions: service conditions, product standard, special-purpose requirements;
- Materials and structure: material selection for body and closure, structural type versus design conditions;
- Sealing arrangement: seal type and seal element selection versus design conditions;
- Strength calculations: shell strength (where the product standard gives no fixed value), shell joint strength, closure and closure-joint strength, operating force or torque;
- Body material forming method and technical requirements: casting method and defect acceptance level, forging method and forging class;
- Correctness of requirements where welding, heat treatment or NDT is involved;
- Correctness of the inspection and test procedure documents.
Inspection and testing (11)
| Item | Key points |
|---|---|
| Appearance and marking | Cast/forged finish, flow arrow, nameplate data matching the drawing |
| Body material properties | Mechanical properties for iron bodies; chemical composition for other materials |
| Critical dimensions | Minimum body wall thickness, minimum stem diameter, body–bonnet bolt thread size, closure assembly joint dimensions |
| Shell strength and seat test | Mandatory for all valves; back-seat test mandatory where a back seat exists (parameters in section 6) |
| Ambient cycling | Solenoid valves 100 pressurised cycles; check valves 20 unloaded cycles; plugging valves 5 insert/withdraw cycles; all others 20 pressurised cycles |
| Closure assembly tensile test | Steel gate valves, DN ≤ 200 mm and PN ≤ 16.0 MPa |
| Seat face hardness | After hardfacing: gate disc, globe disc, check disc, butterfly body or disc, metal-seated ball valve seat and ball |
| Antistatic test | Where applicable (flammable media, non-metallic seat/stem) |
| Vibration resistance | Where applicable (vibration service requirements) |
| Fugitive emission test | Where the stem uses a bellows seal |
| Low-temperature test | Where applicable (design temperature below ambient service) |
The last four are all conditional, and they are the ones most often missed. The trigger is not whether the customer asked, but the design and service: a bellows stem always triggers fugitive emission testing, and flammable service with a non-metallic seat almost always triggers antistatic testing. Discovering a missing item later means booking another test slot.
4. Sampling: two different sizes, base lot of at least five
- Within the same typical structure, two samples of different sizes are drawn according to the intended coverage; the sampling base is at least 5 pieces;
- Where the samples must cover several parameter bands (PN, DN, temperature), more samples are added according to the coverage range;
- For a single-size product, one unit is enough — but then PN* = PN and DN* = DN, with no coverage margin;
- Where PN ≥ 10 MPa and PN×DN ≥ 5000 MPa·mm, or DN ≥ 1000 mm, the base may drop to no fewer than 2 pieces.
“Base” means finished units available for sampling in the same batch, not the two units submitted. An insufficient base is the classic on-site blocker: small custom batches often yield only one or two units, so either the next production run has to be scheduled or an expert demonstration for special structures has to be arranged.
5. Coverage: what you save in test fees, you gamble on certificate validity
Three conditions must be met simultaneously; fail any one and the excess is outside the certificate.
(a) Structural coverage
A globe valve may cover a throttling valve; no other structures cover each other. A ball valve cannot cover a butterfly valve, and a gate valve cannot cover a globe valve. There is no interpretive room here.
(b) Size and pressure class coverage
| Sample PN | Covered PN* | Covered DN* |
|---|---|---|
| PN ≤ 4.0 MPa | PN* ≤ PN | DN* ≤ 2DN |
| 4.0 MPa < PN < 10.0 MPa | PN* < 10.0 MPa | DN* ≤ 2DN |
| 10.0 MPa ≤ PN ≤ 16.0 MPa | PN* ≤ 16.0 MPa | DN* ≤ 2DN |
| 16.0 MPa < PN ≤ 32.0 MPa | PN* ≤ 32.0 MPa | DN* ≤ 2DN |
| PN > 32.0 MPa | PN* ≤ PN | DN* ≤ 2DN |
| Single-size product | PN* = PN | DN* = DN |
Two exceptions to memorise:
- For PN ≥ 10.0 MPa, where 150 mm ≤ DN < 300 mm, the upper limit is DN* < 300 mm — 2DN does not apply up to 600;
- Pressure bands do not round up. A PN16 sample covers up to PN16 and will not stretch to PN25 “because it is close”; a higher class needs another sample.
Example: a DN 80, PN 16 ball valve sample covers the same structure up to DN 160 and PN 16.0 MPa. It does not cover gate valves, nor a PN25 ball valve of the same size.
(c) Temperature range
Set by the sample, with the E1 design temperature not lower than -46 °C. A sample designed for ambient service yields a certificate without cryogenic capability.
6. Pressure and hold time: how hard, how long
| Test | Test pressure | Medium |
|---|---|---|
| Shell strength | 1.5 × ambient maximum allowable working pressure | Water, air or nitrogen, or a non-corrosive liquid of viscosity not above water |
| High-pressure back seat | 1.1 × ambient MAWP | As above |
| High-pressure seat | 1.1 × ambient MAWP or maximum allowable differential | As above |
| Low-pressure back seat / seat | 0.5 – 0.7 MPa | Air or nitrogen |
| Butterfly valve seat | 1.1 × ambient MAWP or differential | Per product standard |
Hold times are banded by size, and the shell and seat columns are not the same figure:
| DN / mm | Shell strength | Seat / back seat |
|---|---|---|
| ≤ 100 | 2 min | 2 min |
| > 100 – 250 | 5 min | 5 min |
| > 250 – 450 | 15 min | 5 min |
| > 450 | 30 min | — |
Three basic requirements are easily overlooked: air must be vented from the body before a liquid test; a high-pressure gas shell or seat test must follow a successful liquid strength test; and no external force that affects seat leakage may be applied at either end during the seat test — over-tightened fixtures produce leakage figures that mean nothing. Medium and ambient temperature stay within 5 – 50 °C.
Two further specifics: for iron-bodied check valves the high-pressure seat test pressure follows the product standard; and for bellows-sealed stems, after the cycling and seat tests the bellows still needs a 0.6 MPa nitrogen tightness test.
7. After issue: four years, renewal and retesting
- Report: issued within 5 working days of test completion, together with the certificate if the result is acceptable;
- Validity: 4 years;
- Renewal: apply between 6 and 12 months before expiry with a self-declaration and supporting documents; renewed for 4 years; renewal may not be applied for twice in succession;
- Conditions: at least 5 production batches per product during the certified period; the agency reviews documents within 20 working days and performs an on-site check (products within coverage, conformity with the sample design and process, key safety performance);
- Marking: the TSX type-test mark goes on the product or the quality certificate.
Seven situations require a fresh type test rather than renewal: a change in design basis or structure needing design verification; a change in the main manufacturing process needing process verification; an expired certificate; a renewal conclusion of non-conformity; relocation of the manufacturing site; a requirement in the safety regulation; or the original agency no longer holding the relevant approval.
8. Five common reasons applications are returned
- Incomplete technical documents: drawings, strength calculations, process documents and production records are the usual gaps — especially calculations still based on an old standard edition;
- Company or international standards without a gap analysis: a clause-by-clause comparison against the regulation’s essential safety requirements plus a declaration of conformity is required, not just a copy of the standard;
- Wrong coverage claims: different structures covering each other, DN beyond 2×, or ignoring the DN < 300 limit at PN ≥ 10 MPa;
- Insufficient sampling base: small custom batches below 5 units, or large valves not prepared at ≥ 2;
- Missing special tests: antistatic, vibration, bellows fugitive emission or low-temperature testing that should have been included.
9. Configuring a bench for pre-testing
Type testing happens at the agency, but nobody wants the first run to be there. Running shell, seat, back-seat and cycling tests in-house first exposes fixture, venting and pressure-stability problems, and aligns the numbers in the technical file. Four things matter on the equipment side:
- Pressure headroom: size for 1.5 × CWP and hold 30 min for DN > 450 shell tests, with an exportable pressure-decay record;
- Controllable clamping: end loads must not affect seat leakage; the fixture needs force or displacement indication;
- Medium and temperature: water or nitrogen for shell and high-pressure seat tests, 0.5 – 0.7 MPa air for low-pressure seat tests, medium at 5 – 50 °C;
- Record fields: pressure–time curve, medium temperature, hold start/end, and leakage units (mm³/s or mL/min) matching the report convention.
For the full method of deriving bench capability from test type, see the valve testing equipment selection guide; the class definitions for shell and seat acceptance are in ISO 5208 leakage rates, and the three bases for hold time in pressure test hold time.
FAQ
With a manufacturing licence, is a type-test certificate still needed?
Yes — they are not substitutes. The licence proves the plant has the production conditions; the type test proves a specific model’s safety performance meets the regulation. Products in scope cannot leave the factory or be used in China without a certificate. Type testing is also not a precondition for licensing, so the two tracks can run in parallel.
Can one sample cover an entire series?
Only within the permitted range: same structural type (a globe valve may cover a throttling valve), PN within the same band, DN no more than 2× (with a 300 mm ceiling at PN ≥ 10 MPa and 150 ≤ DN < 300), and temperature as determined by the sample. Step outside any one of these and another sample is required.
Can the type-test report serve as factory test records?
No. Type testing validates the design on a small number of samples; factory testing requires shell and seat tests on every unit or batch. What a customer audit looks for is the relationship between the two, not one report stretched over all batches.
How early should renewal be started?
From 6 months before expiry, and no earlier than 12 months. Note that renewal cannot be applied for twice in succession — the second expiry requires a full retest, so production and submission planning should start a year ahead.
Specific items, sample quantities, coverage and acceptance criteria follow the official TSG D7002-2023 text and Annex E; the tables above are for quick orientation in certification planning and bench discussions. The same models often need additional special type tests: fire testing in the ISO 10497 vs API 607 comparison, cryogenic testing in ISO 28921-2 vs GB/T 24925, and fugitive emissions in ISO 15848 vs API 624; the entry point for all four standards systems is the valve test standards index.
Related test equipment
Each test above maps to a bench. Pick by valve type and by the item you need to prove:
- Valve comprehensive test bench — pressure, tightness, flow, torque and life cycling on one clamping system
- Valve pressure test machine — shell at 1.5x and seat at 1.1x, with a report per valve
- Pipe and connection leak test bench — pressure-decay and helium methods, judged against a leak-rate limit
- Valve testing equipment range — browse all models by valve type and test item