# Which welding standard applies to your welding? > Choose your product and see which welding standard applies, what you must demonstrate, which acceptance level fits and how much NDT is usual. Fourteen product. Source: https://dehaasprojects.com/en/standard-selector/ Updated on: 2026-11-04 Standard selector Updated: 4 November 2026 In short - Which welding standard applies follows from what you build and what it is for, not from the welding process. - Steel structures fall under EN 1090-2, pressure equipment under the PED and EN 13445, rail vehicles under EN 15085-2 and aluminium under EN 1090-3. - Under EN 1090-2 you derive the execution class EXC1 to EXC4 from the consequence class, the service category and the production category. - The acceptance level usually comes from ISO 5817, and for aluminium from ISO 10042. Updated on 4 November 2026 Which standard applies to your welding does not depend on what you weld but on what you build and what it is for. A steel hall falls under EN 1090-2, the same welding in a pressure vessel falls under the PED, and in a rail vehicle EN 15085 applies. On this page you see per product type which standard applies, what you have to demonstrate, who may do it, which acceptance level fits and how much non destructive testing is usual. Everything below is indicative and meant to point you in the right direction quickly. The binding requirement is always in the design, the contract or the risk assessment. If in doubt, just call: you get an answer from a welding coordinator. ## Which standard applies to your welding? Choose what you build. You immediately see which standard applies, what you have to demonstrate and who may do it. Indicative: the binding requirement is in the design or contract. EN 1090-2 + EN 1090-1 ## Steel structure #### What you have to demonstrate - Execution class EXC1 to EXC4 determined and recorded - WPS and WPQR to ISO 15614-1 within the correct range - Welders qualified to ISO 9606-1 - Welding coordinator with tasks and authority to ISO 14731 - FPC system and CE marking under EN 1090-1 Acceptance level ISO 5817 level B, C or D, tied to the execution class Usual NDT scope EXC2 roughly 0 to 10 percent, EXC3 roughly 10 to 20 percent, EXC4 up to 100 percent on transverse welds #### Who does that WPQRs are issued by a recognised examiner or inspection body. The FPC is assessed by a notified body. #### Determine your execution class (EXC) EN 1090-2 derives the EXC from the consequence class, the service category and the production category. Consequence class (CC) CC1 low consequence CC2 normal consequence CC3 high consequence Service category (SC) SC1 predominantly static SC2 fatigue or seismic Production category (PC) PC1 no welding above S355, no special requirements PC2 higher steel grade, hollow sections or heavy welding Execution class EXC2 [This is where we help: EN 1090 support](/en/services/en-1090-support/)[Read the industry page](/en/industries/steel-construction/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. PED 2014/68/EU + EN 13445 ## Pressure vessel or equipment #### What you have to demonstrate - Classification in category I to IV based on pressure, volume and fluid group - WPS and WPQR approved by a recognised third party - Welder qualifications taken by a recognised third party - NDT scope according to the chosen technical table - Material certificates 3.1 or 3.2 to EN 10204 Acceptance level ISO 5817 level B for most pressure retaining welds Usual NDT scope Follows the chosen technical table: from sampling to 100 percent RT or UT on longitudinal and circumferential welds #### Who does that From category II a notified body or recognised third party organisation is involved in the qualifications. [This is where we help: WPQR qualification](/en/services/wpqr-qualification/)[Read the industry page](/en/industries/pressure-equipment/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 13480 + PED ## Industrial piping #### What you have to demonstrate - Piping class and category determined under the PED - WPS and WPQR matching the material group and wall thickness - Welders qualified to ISO 9606-1, correct position and diameter range - NDT percentage per weld recorded and demonstrable - Pressure test and final reporting complete Acceptance level ISO 5817 level B or C, depending on the piping class Usual NDT scope Usually 5 to 100 percent RT or UT per weld type, recorded in the inspection plan #### Who does that Qualifications within the PED scope run via a recognised third party; day to day control is with the welding coordinator. [This is where we help: NDT coordination](/en/services/ndt-coordination/)[Read the industry page](/en/industries/petrochemical-process-industry/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 14015 of EN 12285 ## Storage tank #### What you have to demonstrate - Choice between aboveground (EN 14015) and underground tank (EN 12285) - WPS and WPQR for the plate thicknesses and joint types in the tank - Welders qualified for the positions occurring - NDT on bottom welds, shell welds and connections - Testing and handover according to the standard Acceptance level ISO 5817 level C for shell welds, level B on critical connections Usual NDT scope Vacuum box on bottom welds, RT or UT on shell welds according to the standard #### Who does that The welding coordinator monitors execution; final inspection often runs via an independent inspection body. [This is where we help: Fabrication inspection](/en/services/fabrication-inspection/)[Read the industry page](/en/industries/tank-fabrication/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. Klasse-eisen (DNV, LR, BV) + IACS ## Ship or ship component #### What you have to demonstrate - Approval of welding procedures by the classification society - Welders qualified to the requirements of that society - Materials with a class certificate - NDT by a qualified NDT company, reporting to the surveyor - Acceptance criteria according to class, not only ISO 5817 Acceptance level The acceptance table of the classification society, not automatically ISO 5817 Usual NDT scope Per weld type, recorded in the NDT plan the surveyor approves #### Who does that The classification society approves and releases. We prepare the dossier and guide the survey. [This is where we help: Third party inspection](/en/services/third-party-inspection-services/)[Read the industry page](/en/industries/shipbuilding/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 15085-2 ## Rail vehicle or component #### What you have to demonstrate - Company certification level CL1 to CL4 - Weld performance class per part (CP A to CP D) from the design drawing - Welding coordinator with the correct authority under EN 15085-2 - WPS and WPQR matching the weld performance class - Assessment by a recognised certification body Acceptance level ISO 5817 level B or C per weld performance class CP A to CP D Usual NDT scope CP A requires full volumetric testing, CP C and D often visual only #### Who does that The certification body assesses the company. The welding coordinator monitors daily execution. [This is where we help: Hire a welding coordinator](/en/services/welding-coordinator/)[Read the industry page](/en/industries/machine-building/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. Machinerichtlijn 2006/42/EG + ISO 3834 ## Machine or machine frame #### What you have to demonstrate - Risk assessment showing which welds are critical - ISO 3834-2, -3 or -4 chosen to match the product - WPS and WPQR for the critical joints - Acceptance level to ISO 5817 (B, C or D) recorded - Technical file complete for the CE declaration Acceptance level ISO 5817 level C for load bearing parts, level D for non critical parts Usual NDT scope Only on the welds the risk assessment marks as critical #### Who does that The manufacturer declares conformity. We make sure the welding part of the file is sound. [This is where we help: ISO 3834 support](/en/services/iso-3834-support/)[Read the industry page](/en/industries/machine-building/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 1090-2 EXC3 of EXC4 + EN 13001 ## Crane or lifting equipment #### What you have to demonstrate - Execution class usually EXC3 or EXC4 due to fatigue loading - Fatigue sensitive welds identified separately on the drawing - Wide NDT scope, often 100 percent on critical welds - Acceptance level ISO 5817 class B on fatigue critical welds - Full traceability from material to welder Acceptance level ISO 5817 level B on fatigue critical welds Usual NDT scope Wide: often 100 percent on transverse welds in the main structure #### Who does that The welding coordinator monitors execution; NDT by a qualified agency under ISO 9712. [This is where we help: QA/QC support](/en/services/qa-qc-inspector/)[Read the industry page](/en/industries/cranes-lifting-equipment/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. ISO 3834 + hygiënisch ontwerp (EHEDG) ## Food or pharmaceutical #### What you have to demonstrate - Hygienic weld design: fully penetrated, smooth and crevice free welds - Orbital welding with recorded parameters where possible - Pickling and passivation, or gaseous root protection demonstrable - Ferrite content and surface roughness within the stated limits - Material certificates 3.1 for all product contact parts Acceptance level ISO 5817 level B, plus requirements on roughness and the root side Usual NDT scope Visual on 100 percent of the product contact side, endoscopy on closed piping #### Who does that The client sets the hygiene requirements. We translate them into WPS, control and reporting. [This is where we help: Welding engineering advice](/en/services/welding-engineering-services/)[Read the industry page](/en/industries/food-pharmaceutical/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. PED + EN 13445 of EN 13480 ## Hydrogen or energy transition #### What you have to demonstrate - Material selection suitable for hydrogen at the chosen pressure - Low hardness in the heat affected zone, recorded in the WPS - Strict NDT scope and acceptance criteria - Traceability down to heat number - Alignment with the notified body on the category Acceptance level ISO 5817 level B, with a hard upper limit on hardness in the HAZ Usual NDT scope High percentage of RT or UT, often 100 percent, plus hardness testing #### Who does that Qualifications run via a recognised third party. We draft the WPS and monitor execution. [This is where we help: Independent welding consultant for technical welding issues](/en/services/welding-consultant/)[Read the industry page](/en/industries/hydrogen-energy-transition/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 1090-2 EXC3 of EXC4 + ROK of RTD-richtlijn ## Bridge or civil structure #### What you have to demonstrate - Execution class EXC3 or EXC4 from the design or specification - Fatigue details and their detail category named on the drawing - WPS and WPQR with impact testing at the correct temperature - Welding coordinator at IWE level for EXC4 - Complete welding file with traceability per weld Acceptance level ISO 5817 level B, with extra requirements from the client specification Usual NDT scope 100 percent on transverse welds in tension zones, 10 to 20 percent on longitudinal welds #### Who does that The client or their supervisor approves the welding plan. We draft it and monitor execution. #### Determine your execution class (EXC) EN 1090-2 derives the EXC from the consequence class, the service category and the production category. Consequence class (CC) CC1 low consequence CC2 normal consequence CC3 high consequence Service category (SC) SC1 predominantly static SC2 fatigue or seismic Production category (PC) PC1 no welding above S355, no special requirements PC2 higher steel grade, hollow sections or heavy welding Execution class EXC2 [This is where we help: EN 1090 support](/en/services/en-1090-support/)[Read the industry page](/en/industries/steel-construction/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 1090-3 + ISO 15614-2 + ISO 9606-2 ## Aluminium structure #### What you have to demonstrate - Execution class to EN 1090-3, not EN 1090-2 - WPS and WPQR to ISO 15614-2, with the correct alloy group - Welders qualified to ISO 9606-2 - Acceptance level to ISO 10042, not ISO 5817 - Attention to softening in the heat affected zone Acceptance level ISO 10042 level B, C or D, the aluminium counterpart of ISO 5817 Usual NDT scope RT or UT on critical welds; penetrant testing instead of magnetic particle testing #### Who does that The same route as steel, but with different standards. In practice these are often mixed up. [This is where we help: WPQR qualification](/en/services/wpqr-qualification/)[Read the industry page](/en/industries/machine-building/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. EN 13480 of ISO 3834 + ASME B31.3 ## Stainless steel process plant #### What you have to demonstrate - Correct material group in the WPS (304, 316, duplex or superduplex) - Root protection with a recorded oxygen limit - Ferrite content measured on duplex, within 30 to 70 percent - Pickling and passivation or mechanical treatment demonstrable - PMI checks on delivered material and consumables Acceptance level ISO 5817 level B, plus requirements on discolouration and ferrite content Usual NDT scope Visual on 100 percent, RT or UT on an agreed percentage, plus PMI #### Who does that The client sets the requirements in the specification. We translate them into WPS and control plan. [This is where we help: Welding engineering advice](/en/services/welding-engineering-services/)[Read the industry page](/en/industries/petrochemical-process-industry/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. ISO 5817 + de oorspronkelijke productnorm ## Repair or rejected welding #### What you have to demonstrate - Root cause analysis: why was the weld rejected - A repair WPS covering gouging and rewelding - A limit on the number of repairs in the same place - Re-inspection with the same method and acceptance level - Recording in an NCR with a substantiated disposition Acceptance level The same level as the original weld, unless agreed otherwise in writing Usual NDT scope 100 percent on the repair, with the same method that found the defect #### Who does that A second opinion from an independent party makes the difference in a rejection dispute. [This is where we help: Hire a welding inspector](/en/services/welding-inspector/)[Read the industry page](/en/industries/steel-construction/) Add this to my request -> Indicative. The binding standard and class follow from the design, the contract or the risk assessment. ## How to determine your execution class (EXC) 1 ### Determine the consequence class (CC) CC1 for low consequence of failure, CC2 for normal consequence and CC3 where failure has major consequences for life or surroundings. The consequence class comes from EN 1990 annex B and should be set by the designer. 2 ### Determine the service category (SC) SC1 for predominantly statically loaded structures, SC2 as soon as fatigue, seismic loading or crane runways are involved. 3 ### Determine the production category (PC) PC1 if no welding above S355 takes place and there are no special requirements, PC2 for higher steel grades, hollow sections with node welds, heat treatment or heavy welding. 4 ### Read off the execution class With these three choices you read the execution class EXC1 to EXC4 from table B.3 of EN 1090-2. In Dutch steel construction EXC2 is the most common. 5 ### Have it recorded The execution class belongs on the drawing or in the specification. If it is not there, ask for it: it drives your WPS, your NDT scope and your acceptance criteria. ## All fourteen product types - [Steel structure](#nk-staalbouw) EN 1090-2 + EN 1090-1 - [Pressure vessel or equipment](#nk-druk) PED 2014/68/EU + EN 13445 - [Industrial piping](#nk-leiding) EN 13480 + PED - [Storage tank](#nk-tank) EN 14015 of EN 12285 - [Ship or ship component](#nk-schip) Klasse-eisen (DNV, LR, BV) + IACS - [Rail vehicle or component](#nk-spoor) EN 15085-2 - [Machine or machine frame](#nk-machine) Machinerichtlijn 2006/42/EG + ISO 3834 - [Crane or lifting equipment](#nk-hijs) EN 1090-2 EXC3 of EXC4 + EN 13001 - [Food or pharmaceutical](#nk-food) ISO 3834 + hygiënisch ontwerp (EHEDG) - [Hydrogen or energy transition](#nk-waterstof) PED + EN 13445 of EN 13480 - [Bridge or civil structure](#nk-brug) EN 1090-2 EXC3 of EXC4 + ROK of RTD-richtlijn - [Aluminium structure](#nk-aluminium) EN 1090-3 + ISO 15614-2 + ISO 9606-2 - [Stainless steel process plant](#nk-rvs) EN 13480 of ISO 3834 + ASME B31.3 - [Repair or rejected welding](#nk-reparatie) ISO 5817 + de oorspronkelijke productnorm ## Frequently asked questions Frequently asked questions about standards and execution classes ### How do I know which welding standard applies to my product? That follows from the product and its application, not from the welding process. A steel load bearing structure falls under EN 1090-2, pressure equipment under the PED and EN 13445 or EN 13480, a rail vehicle under EN 15085-2 and a machine under the Machinery Directive with ISO 3834 underneath. If it is not in the specification, look at the directive that applies to the end product. ### What is the difference between ISO 3834 and EN 1090? ISO 3834 sets requirements for quality assurance of the welding process in your company. EN 1090 sets requirements for the product, the steel structure, and refers to ISO 3834 for the welding assurance. ISO 3834 alone therefore does not give you CE marking; EN 1090-1 does. ### Who determines the execution class EXC? The designer, in the design. The EXC follows from the consequence class, the service category and the production category and belongs on the drawing or in the specification. If it is not there, ask for it before you start welding: it drives your WPS, your NDT scope and your acceptance criteria. ### Which acceptance level goes with which execution class? As a rule of thumb: EXC1 goes with ISO 5817 level D, EXC2 with level C plus a number of level B requirements, and EXC3 and EXC4 with level B. EN 1090-2 gives the exact link per imperfection; for aluminium ISO 10042 applies instead of ISO 5817. ### May a company with an EXC2 certificate carry out EXC3 work? No. The FPC certificate is issued for a given execution class. Work in a higher class requires an extension of the certification, with the matching welding coordination, qualifications and NDT scope. ### How much non destructive testing is needed? That depends on the standard, the class and the weld type. Under EN 1090-2 it runs from almost nothing in EXC1 to 100 percent on transverse welds in EXC4. For pressure equipment the scope follows from the chosen technical table of EN 13445. The percentage belongs in the inspection plan before welding starts. ## A question about a welding standard, a WPS or an inspection? Just ask it. You get a personal answer from a welding coordinator who has done the work, not from a salesperson. [Send your request](/en/quote/) [Call 06 29 72 37 91](tel:+31629723791) --- DEHAAS Inspection, Manufacturing & Welding Consultancy, Rypsterdyk 2, 9036 JG Menaam. Phone 06 29 72 37 91, e-mail cdehaas@dehaasprojects.com, https://dehaasprojects.com.