# Knowledge centre: welding standards, qualifications and inspection

> Over eighty articles on EN 1090, ISO 3834, WPS and WPQR, welder qualifications, NDT, materials and acceptance criteria. Written for practice.

Source: https://dehaasprojects.com/en/knowledge-centre/
Updated on: 2026-11-04
No marketing copy but answers: which standard applies, what you have to demonstrate and where it goes wrong in practice. Search by topic or browse the whole list.

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- [ASME IX vs EN ISO 15614-1: two systems for procedure qualification](/en/knowledge-centre/asme-ix-vs-iso-15614/) ASME IX or EN ISO 15614-1? The differences in structure (PQR, WPS, WPQ versus WPQR), variables, testing.
- [ASME Section IX explained](/en/knowledge-centre/asme-section-ix-explained/) ASME Section IX explained: QW and QB, P-numbers and F-numbers, essential and supplementary variables, WPS.
- [AWS D1.1 versus the European standards: the key differences](/en/knowledge-centre/aws-d1-1-vs-en-standards/) How AWS D1.1 compares with EN 1090, EN ISO 15614-1 and ISO 9606-1: structure, prequalified WPSs and what it.
- [AWS D1.1 prequalified WPS: rules, limits and common mistakes](/en/knowledge-centre/aws-d1-1-prequalified-wps/) AWS D1.1 prequalified WPS explained: when you can skip procedure testing, when a PQR is required.
- [Welding aluminium: 5083 and 6082](/en/knowledge-centre/welding-aluminium-5083-6082/) Welding aluminium calls for a different approach than steel: oxide film, hydrogen porosity, strength loss.
- [Welding austenitic stainless steel: 304 and 316](/en/knowledge-centre/welding-304-316-stainless/) Welding 304 and 316 without distortion, carbide precipitation or loss of corrosion resistance: filler.
- [Image quality in radiography: ISO 19232](/en/knowledge-centre/iso-19232-image-quality/) Wire indicators, duplex wire indicators and the required image quality class: how to demonstrate that.
- [Selecting shielding gas](/en/knowledge-centre/selecting-shielding-gas/) Which shielding gas for which material and process? M21, C1, I1 and the mixtures, with their effect.
- [CE marking of steel structures under EN 1090-1](/en/knowledge-centre/ce-marking-steel-structures/) CE marking of structural steelwork under EN 1090-1: how the DoP and FPC work, the role of the notified body.
- [The NCR: recording, resolving and learning from non-conformities](/en/knowledge-centre/ncr-non-conformity/) Writing an NCR (non-conformity report): when to raise one, what it must contain, the dispositions use as is.
- [The procedure qualification record (PQR): what it is and how it works](/en/knowledge-centre/procedure-qualification-record-pqr/) What is a procedure qualification record under ASME IX? How WPS and PQR relate, what a PQR contains, how it.
- [Calculating the throat thickness of a fillet weld](/en/knowledge-centre/fillet-weld-throat-calculation/) Throat or leg length? How to calculate the required throat thickness of a fillet weld to EN 1993-1-8.
- [The welding coordinator under ISO 14731: when, who and what](/en/knowledge-centre/welding-coordinator-iso-14731/) When a welding coordinator is required under ISO 14731, which tasks and responsibilities the role covers.
- [Selecting the weld quality level: B, C or D](/en/knowledge-centre/selecting-weld-quality-level/) How to choose between quality levels B, C and D of ISO 5817 with justification: balancing loading.
- [Planning the welding sequence](/en/knowledge-centre/welding-sequence-planning/) A considered welding sequence saves more than the best straightening: balanced welding, back stepping.
- [Full penetration: when required and how to prove it](/en/knowledge-centre/full-penetration-requirements/) When is full penetration required, when does a partial penetration or fillet weld suffice, and how do you.
- [Welding duplex stainless steel: key considerations](/en/knowledge-centre/welding-duplex-stainless/) Welding duplex stainless steel: ferrite austenite balance, the heat input window, filler selection.
- [EN 13445: unfired pressure vessels](/en/knowledge-centre/en-13445-pressure-vessels/) EN 13445 explained: testing groups, joint coefficient, NDT extent and the relationship with the PED. Why.
- [EN 15085: welding of railway vehicles](/en/knowledge-centre/en-15085-railway-welding/) Certification to EN 15085-2 for welding railway vehicles: certification levels CL1 to CL4, weld performance.
- [Execution classes under EN 1090-2: EXC1 to EXC4 explained](/en/knowledge-centre/en-1090-execution-classes/) How execution classes EXC1 to EXC4 are determined under EN 1090-2 and what each class means for welding.
- [How to write an ITP that works in practice](/en/knowledge-centre/how-to-write-an-itp/) How to write an ITP (inspection and test plan): structure, hold, witness and review points, responsibilities.
- [Adopting a WPQR from a third party](/en/knowledge-centre/adopting-third-party-wpqr/) Adopting a WPQR from a supplier, a sister company or a previous employer: when it is permitted, which.
- [Writing a pWPS: variables, sources and pitfalls](/en/knowledge-centre/how-to-write-a-pwps/) Writing a pWPS for a welding procedure qualification: the variables it must contain, where to source.
- [Essential variables: what invalidates a qualification](/en/knowledge-centre/wps-essential-variables/) Which changes invalidate a welding procedure qualification? The essential variables of ISO 15614-1 and ASME.
- [FAT and final inspection without surprises](/en/knowledge-centre/fat-final-inspection/) How to prepare a FAT and final inspection: checklist, the role of the independent inspector, digital release.
- [Factory production control (FPC) under EN 1090-1](/en/knowledge-centre/factory-production-control/) Factory production control (FPC) under EN 1090-1: what it must cover, how to set it up in practice.
- [Ferrite measurement in stainless and duplex weld metal](/en/knowledge-centre/ferrite-measurement-stainless/) Why ferrite content in austenitic and duplex weld metal is measured, how the ferritescope works and which.
- [Welding fine grain steel: S460 to S690](/en/knowledge-centre/welding-high-strength-steel-s460-s690/) Welding S460, S550 and S690: keeping heat input inside the window, preheat, low hydrogen practice.
- [Validity and revalidation of welder qualifications](/en/knowledge-centre/revalidating-welder-qualifications/) Validity and revalidation of welder qualifications under ISO 9606-1: the six-month confirmation.
- [Welding cast iron](/en/knowledge-centre/welding-cast-iron/) Repairing cast iron by welding: grey versus ductile iron, cold welding with nickel electrodes, hot welding.
- [Hardness testing of welded joints](/en/knowledge-centre/weld-hardness-testing/) Hardness testing to ISO 9015 and ISO 6507: where to measure in weld and HAZ, which limits apply.
- [The MRB and MDR: building the project dossier properly](/en/knowledge-centre/mrb-mdr-structure/) How to build an MRB or MDR: which documents belong in it, in what order, and why you should compile.
- [The quality control plan for your fabrication project](/en/knowledge-centre/quality-control-plan/) What belongs in a quality control plan (QCP) for fabrication projects, how it differs from an ITP and how.
- [ISO 15614-1: the welding procedure test explained](/en/knowledge-centre/iso-15614-1-explained/) How does a welding procedure qualification to EN ISO 15614-1 work? Test coupon, testing programme, level 1.
- [ISO 3834 parts 2, 3 and 4: which part fits your company](/en/knowledge-centre/iso-3834-parts/) ISO 3834 has three certifiable parts. Which part suits which company, what each part requires, and how.
- [ISO 5817 quality levels B, C and D: selecting and applying](/en/knowledge-centre/iso-5817-quality-levels/) What the ISO 5817 quality levels B, C and D mean, how to select the right level for your welded work and how.
- [Welding copper and bronze](/en/knowledge-centre/welding-copper-and-bronze/) Welding copper, brass and bronze: thermal conductivity, preheat, oxygen free copper and the fumes from zinc.
- [Qualification range for thickness and diameter under EN ISO 15614-1](/en/knowledge-centre/qualification-range-thickness-diameter/) How does the qualification range for thickness and diameter work under EN ISO 15614-1? The tables explained.
- [Weld defects: recognition, causes and prevention](/en/knowledge-centre/weld-defects-causes/) How to recognise common weld defects, from porosity and lack of fusion to cracks and undercut: causes.
- [CWI vs IWI: welding inspector certification compared](/en/knowledge-centre/cwi-vs-iwi-welding-inspector/) Welding inspector certification compared: AWS CWI, IIW IWI, CSWIP 3.1 and ISO 9712 VT. Levels, validity.
- [WPQR cost and lead time: where the money goes and how long it takes](/en/knowledge-centre/wpqr-cost-lead-time/) What drives the cost and lead time of a welding procedure qualification? The cost items of a WPQR, what.
- [Joint preparation: which form when](/en/knowledge-centre/joint-preparation-iso-9692/) V, X, U or J: which joint preparation do you choose and why? Included angle, root face, gap and their.
- [MAG welding process 135 and cored wire processes 136 and 138](/en/knowledge-centre/gmaw-mag-process-135/) Welding process 135 (MAG) and the cored wire processes 136 and 138: metal transfer modes, shielding gases.
- [Welding fume: limits and duties](/en/knowledge-centre/welding-fume-safety/) Welding fume and occupational health law: limits for chromium VI, manganese and nickel, mandatory local.
- [Welding under the PED 2014/68/EU: categories and approvals](/en/knowledge-centre/ped-welding-requirements/) What the PED 2014/68/EU requires for welding: categories, permanent joints, and approval of welding.
- [Welder certification compared: AWS, ASME IX and ISO 9606-1](/en/knowledge-centre/welder-certification-aws-asme-iso/) Welder certification compared: AWS D1.1, the AWS Certified Welder program, ASME IX WPQ and ISO 9606-1. Who.
- [Welder qualification to ISO 9606-1](/en/knowledge-centre/welder-qualification-iso-9606/) How welder qualification to ISO 9606-1 works: the structure of the standard, essential variables, ranges.
- [Reading welding symbols to ISO 2553](/en/knowledge-centre/welding-symbols-iso-2553/) Welding symbols explained: the reference line, arrow side and other side, a and z dimensions, length.
- [Controlling weld distortion: causes, types and measures](/en/knowledge-centre/controlling-weld-distortion/) How to control weld distortion: how shrinkage arises, types of distortion, and how welding sequence.
- [Magnetic particle testing (MT) of welded joints](/en/knowledge-centre/mt-magnetic-particle-testing/) Magnetic particle testing to ISO 17638: yoke technique, field strength, cross magnetisation.
- [Material certificates 3.1 and 3.2 to EN 10204](/en/knowledge-centre/material-certificates-3-1-3-2/) Material certificates to EN 10204: the difference between 2.1, 2.2, 3.1 and 3.2, who signs, what to require.
- [NDT personnel to ISO 9712: levels, responsibilities and validity](/en/knowledge-centre/iso-9712-ndt-personnel/) Qualification and certification of NDT personnel to ISO 9712: levels 1, 2 and 3, who may do what, methods.
- [Welding nickel alloys and Inconel](/en/knowledge-centre/welding-nickel-alloys-inconel/) Welding Inconel 625, 825 and Alloy 59: sluggish weld pool, hot cracking, dilution in overlay welding.
- [Submerged arc welding (121): productive and controllable](/en/knowledge-centre/submerged-arc-welding-121/) Submerged arc welding (121): high deposition, applications from tanks to cladding, wire flux combinations.
- [Dissimilar metal welds: stainless to carbon steel](/en/knowledge-centre/dissimilar-metal-welds/) Welding stainless to carbon steel: choosing filler metal, controlling dilution, carbon diffusion.
- [Operator qualification to ISO 14732 for mechanised and orbital welding](/en/knowledge-centre/operator-qualification-iso-14732/) Operator qualification to ISO 14732 for robotic, mechanised and orbital welding: when an operator rather.
- [PWHT: post weld heat treatment explained](/en/knowledge-centre/pwht-post-weld-heat-treatment/) Post weld heat treatment: when PWHT is required, which temperatures and holding times apply, and how.
- [Penetrant testing (PT) of welded joints](/en/knowledge-centre/pt-penetrant-testing/) Penetrant testing to ISO 3452: method, dwell times, colour contrast versus fluorescent, and the acceptance.
- [Phased array and TOFD](/en/knowledge-centre/phased-array-tofd/) Phased array (PAUT) and TOFD as a replacement for radiography: how they work, what ISO 13588 and ISO 10863.
- [Punch list management: from open item to clean handover](/en/knowledge-centre/punch-list-management/) How to manage a punch list: classify items as A, B or C, record them clearly, follow them up and close them.
- [Radiographic testing (RT) of welded joints](/en/knowledge-centre/rt-radiographic-testing/) How radiographic weld testing works: X-ray versus gamma, image quality to ISO 19232, digital radiography.
- [Robot welding: qualification and control](/en/knowledge-centre/robot-welding-qualification/) Qualifying robot welding to ISO 15614 and ISO 14732: operator qualification, programme control, seam.
- [Welding wear resistant steel](/en/knowledge-centre/welding-wear-resistant-steel/) Welding wear plate such as Hardox 400 and 500: preheat, heat input, undermatching consumables.
- [TIG welding (141) and orbital welding of pipework](/en/knowledge-centre/tig-141-orbital-welding/) TIG welding (141) and orbital welding of stainless and titanium pipework: when to choose TIG, backing gas.
- [Welding titanium](/en/knowledge-centre/welding-titanium/) Welding titanium demands full shielding until below 400 degrees: trailing shields, chambers, colour.
- [Selecting filler metal](/en/knowledge-centre/selecting-filler-metal/) How to select the right filler metal: reading the classification, matching versus undermatching, hydrogen.
- [Tolerances to EN 1090-2](/en/knowledge-centre/tolerances-en-1090-2/) Essential and functional tolerances in EN 1090-2: what is mandatory, what is negotiable, how to measure.
- [Ultrasonic testing (UT) of welded joints](/en/knowledge-centre/ut-ultrasonic-testing/) Ultrasonic weld testing to ISO 17640: angle probes, testing levels, calibration and why UT finds cracks.
- [Vendor inspection abroad: control of quality at a distance](/en/knowledge-centre/vendor-inspection-abroad/) Vendor inspection abroad: the typical risks, the right inspection stages, reporting and desk expediting.
- [Heat tint on stainless welds: pickling and passivation](/en/knowledge-centre/stainless-heat-tint-pickling/) Heat tint on stainless steel welds: what the colours mean, acceptance criteria, backing gas with oxygen.
- [Fatigue of welded joints](/en/knowledge-centre/fatigue-of-welded-joints/) Why welds fail under fluctuating load: detail categories to EN 1993-1-9, the role of the weld toe.
- [Welding galvanised steel](/en/knowledge-centre/welding-galvanised-steel/) Welding galvanised steel: zinc fume and metal fume fever, porosity, liquid metal embrittlement and restoring.
- [Visual testing of welds to ISO 17637](/en/knowledge-centre/iso-17637-visual-testing/) Visual testing of welds to ISO 17637: lighting, viewing distance and angle, tools, timing.
- [Visual weld inspection: from preparation to report](/en/knowledge-centre/visual-weld-inspection-method/) How does a proper visual weld inspection work? Preparation, measuring tools, assessment against ISO 5817.
- [Preheating in welding: when is it required](/en/knowledge-centre/preheating-when-required/) When is preheating required in welding? Carbon equivalent, thickness, hydrogen control, practical execution.
- [When do you need a WPQR?](/en/knowledge-centre/when-do-you-need-a-wpqr/) When is a WPQR mandatory? A practical overview of the requirements in EN 1090-2, ISO 3834, the PED.
- [Calculating and controlling heat input](/en/knowledge-centre/calculating-heat-input/) How to calculate welding heat input: the formula, thermal efficiency factors per process, and why control.
- [WPS versus WPQR: what is the difference?](/en/knowledge-centre/wps-vs-wpqr-difference/) WPS and WPQR are not the same document. Learn how the pWPS, the qualification record and the welding.
- [Preventing hydrogen cracking: mechanism and measures](/en/knowledge-centre/preventing-hydrogen-cracking/) How to prevent hydrogen cracking and cold cracking: mechanism, risk factors and countermeasures, from.
- [Weld map and weld log: traceability for every weld](/en/knowledge-centre/weld-map-weld-log/) Why a weld map and weld log are essential: traceability per weld, what to record, and how to set them up.
- [Choosing the right NDT method for a welded joint](/en/knowledge-centre/choosing-ndt-method/) Which NDT method suits which welded joint? VT, PT, MT, UT and RT compared on application, strengths.
- [How to determine whether an existing WPQR covers your application](/en/knowledge-centre/wpqr-validity-range/) Is your existing WPQR valid for a new job? How to check material group, thickness, process, position.

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DEHAAS Inspection, Manufacturing & Welding Consultancy, Rypsterdyk 2, 9036 JG Menaam.
Phone 06 29 72 37 91, e-mail cdehaas@dehaasprojects.com, https://dehaasprojects.com.