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ASME STP-PT-002-2005 — ASME Section I PED Guide: Use of ASME Section I to Meet the EC Pressure Equipment Directive (97/23/EC)
🇪🇺 ASME STP-PT-002-2005 (STP/PT-002) is an important compliance guide published by ASME and ASME ST-LLC for ASME stamp holders worldwide, entitled “ASME Section I PED Guide — Supplement to Guide for ASME Stamp Holders: Use of ASME Section I to Meet the EC Pressure Equipment Directive (97/23/EC).” After the mandatory implementation of the European Pressure Equipment Directive (PED 97/23/EC), manufacturers of power boilers and pressure equipment built to the ASME Code and exporting to the EU market faced the practical question of how to use ASME Section I (Power Boilers) as the basis for PED conformity. This guide provides a systematic technical and administrative path to answer that question, supplementing the earlier Section VIII Division 1 PED guide.
💡 Key background: the ASME Code is a “non-harmonized standard” and the PED does not directly endorse it. Manufacturers must work with a Notified Body (NB) to demonstrate that products designed and built to ASME Section I satisfy the Essential Safety Requirements (ESRs) of PED Annex I, complete the applicable conformity assessment modules, and only then affix the CE marking to enter the EU market.
1. Guide Structure and Scope 📌
The guide consists of four parts:
- Part I — update of issues on using the ASME Code to meet the PED: material specifications (approval path for non-harmonized materials), qualification of NDE personnel (alignment of SNT-TC-1A-type systems with EN standards), and discussions with the European Commission;
- Part II — PED overview: national regulatory background, intent of the PED, principles, types of requirements, scope, hazard categories, conformity assessment procedures, Notified Bodies, CE marking, and Essential Safety Requirements;
- Part III — detailed comparison of the technical requirements of ASME Section I with PED 97/23/EC Annex I, including notes on Section I requirements, additional considerations for Annex I ESRs, and quantitative requirements in Annex I to be applied as a general rule (safety factors, joint efficiencies, hydrostatic test pressure formula);
- Part IV — an “Annex ZA” for Section I power boilers, instructing what additional tasks must be completed to meet the administrative requirements of the PED.
⚠️ This supplement must be used together with the existing “Guide for ASME Stamp Holders on Using Section VIII, Division 1 to Meet the EC PED.” Generic content — the EU New Approach, hazard categories, and combinations of conformity assessment modules — is already covered there and is not reproduced here; this supplement focuses on Section I-specific technical comparisons and the Annex ZA.
2. PED Framework and Compliance Path 🔬
PED 97/23/EC entered a transition period on November 29, 1999 and became mandatory on May 29, 2002 (May 30, 2002 for certain articles). Its core mechanisms include:
- Scope: pressure equipment with a maximum allowable pressure PS greater than 0.5 bar (vessels, boilers, piping, safety accessories, etc.), classified into four hazard categories (I–IV) by volume, pressure, and fluid hazard;
- Conformity assessment procedures: different assessment module combinations (e.g., A, B, C1, D, H) selected by hazard category, covering internal design checks, final assessment, production surveillance, and quality systems;
- Notified Body: the third-party body performing conformity assessment; the manufacturer must contract with it and accept its audits;
- CE marking: affixed after the product satisfies all applicable requirements and the assessment is completed, after which the product may be placed on the EU market.
| Hazard Category | Typical Modules | Third-Party Involvement | Typical Products |
|---|---|---|---|
| Category I | Module A (internal production control) | Low (self-inspection) | Small low-pressure vessels, simple pressure vessels |
| Category II | Modules A1 / D1 / E1, etc. | Medium (partial third-party verification) | Medium pressure equipment |
| Category III | Modules B+C1, B1+F, H, etc. | High (design review + final assessment) | Power boilers, large pressure vessels |
| Category IV | Modules B+D, B+F, G, H1, etc. | Highest (full-process third-party surveillance) | Steam boilers, high-pressure vessels with hazardous fluids |
💡 For power boiler manufacturers, the key path is: complete design/manufacture per Section I → use Part III of this guide to compare each ESR of PED Annex I → confirm the assessment modules with the Notified Body → complete the additional tasks (material approval, NDE personnel recognition, final assessment) → affix CE marking.
3. Technical Comparison of ASME Section I with PED Annex I 📊
Part III is the core of the document: each ESR of PED Annex I is mapped to the corresponding Section I clauses, marked as “satisfied / not satisfied / requires additional consideration.” The quantitative requirements to be applied as a general rule deserve special attention:
- Safety factors for allowable stresses (Annex I §7.1.2): the PED requires minimum safety factors relative to yield and tensile strength (e.g., baseline values of 1.5/2.4 for austenitic and non-austenitic steels), which differ from the ASME Section I allowable stress system based on 4:1 tensile and 1.67:1 yield margins — conversion checks are needed;
- Joint efficiencies (Annex I §7.2): the PED specifies joint efficiencies by joint type and extent of examination, which must be matched against the Section I joint efficiency tables and NDE requirements;
- Hydrostatic test pressure formula (Annex I §7.4): the PED provides the formula for hydrostatic test pressure; manufacturers must verify their test procedures against it.
| Item | PED Annex I Requirement | ASME Section I Equivalent | Interface Point |
|---|---|---|---|
| Allowable stress safety factors | §7.1.2 minimum safety factors | 4:1 tensile / 1.67:1 yield system | Re-verify material allowables against PED baselines |
| Joint efficiencies | §7.2 by joint and examination | Joint efficiency tables + RT requirements | Match efficiencies to examination extent |
| Hydrostatic test pressure | §7.4 formula given | Section I hydrostatic test chapter | Check test pressure against the PED formula |
| Material approval | Harmonized standard / specific material assessment | Section I material chapter (SA materials) | Non-harmonized materials need NB assessment |
| NDE personnel qualification | EN 473 / ISO 9712 system | SNT-TC-1A system | Equivalence recognized as required by the NB |
🚨 A common misconception: holding ASME stamps (S, PP, A, etc.) does not automatically satisfy the PED. CE marking is an independent legal requirement; the ASME stamp and Authorized Inspector (AI) system cannot replace Notified Body conformity assessment. The two can run in parallel and complement each other, but both must be completed separately.
4. Annex ZA and Engineering Practice Essentials 🛠️
The “Annex ZA (power boiler version for Section I)” in Part IV lists the additional tasks required to satisfy PED administrative requirements, for example:
- 📋 Technical documentation: assemble the technical file per PED Annex VII (design, materials, manufacturing, examination records) for review by the Notified Body;
- 📊 Hazard category determination: correctly determine the category from product parameters (PS, V, fluid group) and select the corresponding assessment modules;
- 🔧 Notified Body interface: reach a written agreement with the NB in advance on design review scope, witness points, and report formats;
- 🏷️ CE marking management: define marking position, accompanying documents (Declaration of Conformity), and post-marking surveillance responsibilities.
✅ Practical recommendation: combine the “Section I design package + PED Annex I gap list + Notified Body interface plan” into a single “compliance work package” launched in parallel at project start, avoiding ESR gaps discovered near delivery that would delay export schedules.
5. Frequently Asked Questions ❓
❓ Q: What is the relationship between the PED and ASME Section I?
A: The PED is an EU legal directive setting the essential safety requirements for pressure equipment entering the EU market; ASME Section I is one of the “non-harmonized standards” manufacturers may use as a technical basis for meeting the ESRs, but it cannot automatically waive PED conformity assessment and CE marking obligations.
A: The PED is an EU legal directive setting the essential safety requirements for pressure equipment entering the EU market; ASME Section I is one of the “non-harmonized standards” manufacturers may use as a technical basis for meeting the ESRs, but it cannot automatically waive PED conformity assessment and CE marking obligations.
❓ Q: What does “non-harmonized standard” mean?
A: It means a standard not listed in the Official Journal of the EU and without “harmonized” status. Using a harmonized standard gives a presumption of conformity with the ESRs; using a non-harmonized standard (such as ASME) requires demonstration of conformity through Notified Body assessment — a more complex but fully feasible path.
A: It means a standard not listed in the Official Journal of the EU and without “harmonized” status. Using a harmonized standard gives a presumption of conformity with the ESRs; using a non-harmonized standard (such as ASME) requires demonstration of conformity through Notified Body assessment — a more complex but fully feasible path.
❓ Q: Which products fall under the PED?
A: Vessels, boilers, piping, safety accessories, and pressure accessories with a maximum allowable pressure PS greater than 0.5 bar, plus certain combinations. Small low-pressure equipment (e.g., products under the Simple Pressure Vessels Directive) has separate exemptions.
A: Vessels, boilers, piping, safety accessories, and pressure accessories with a maximum allowable pressure PS greater than 0.5 bar, plus certain combinations. Small low-pressure equipment (e.g., products under the Simple Pressure Vessels Directive) has separate exemptions.
❓ Q: Can the ASME stamp replace CE marking?
A: No. The ASME stamp certifies conformance to the ASME Code (witnessed by an AI); the CE marking certifies conformance to EU legislation (assessed by a Notified Body). The legal bases differ, and products exported to the EU must satisfy both.
A: No. The ASME stamp certifies conformance to the ASME Code (witnessed by an AI); the CE marking certifies conformance to EU legislation (assessed by a Notified Body). The legal bases differ, and products exported to the EU must satisfy both.
