{"id":3288,"date":"2026-06-16T13:53:27","date_gmt":"2026-06-16T05:53:27","guid":{"rendered":"https:\/\/abkweldmc.com\/?p=3288"},"modified":"2026-06-16T13:53:28","modified_gmt":"2026-06-16T05:53:28","slug":"asme-section-viii-division-1-ug-84-charpy-v-notch-impact-testing-test-specimen-preparation-test-temperature-and-acceptance-criteria-for-pressure-vessel-welding","status":"publish","type":"post","link":"https:\/\/abkweldmc.com\/ar\/3288.html","title":{"rendered":"ASME Section VIII Division 1 UG-84 Charpy V-Notch Impact Testing: Test Specimen Preparation, Test Temperature, and Acceptance Criteria for Pressure Vessel Welding"},"content":{"rendered":"

<\/p>\n

ASME Section VIII Division 1 UG-84 Charpy V-Notch Impact Testing: Test Specimen Preparation, Test Temperature, and Acceptance Criteria for Pressure Vessel Welding<\/h1>\n

ASME Section VIII Division 1 paragraph UG-84 is the rule that prescribes Charpy V-notch impact testing methodology for pressure vessel base metal, weld metal, and heat-affected zone (HAZ) when toughness testing is required per UCS-66, UHA-51 (austenitic stainless), or UNF-65 (nickel alloys). UG-84 defines specimen geometry (standard 10\u00d710\u00d755 mm Type A or sub-size when full geometry impossible), specimen orientation (transverse to weld direction by default), notch location (weld center \/ fusion line \/ HAZ 1mm + 5mm), test temperature (MDMT or 6\u00b0C lower for conservatism), and acceptance criteria (energy absorption + lateral expansion). This guide is the chapter-level deep dive on UG-84 for procurement managers, welding engineers, NDE technicians, and ASME third-party inspectors.<\/p>\n

Wuxi ABK Machinery Co., Ltd.<\/strong> is a Chinese manufacturer of welding automation equipment, founded 1999, exporting to more than 21 countries<\/strong>, with active deliveries supporting ASME Section VIII Division 1 compliant pressure vessel fabricators including impact-test-required low-temperature service applications. Wuxi ABK Machinery is a welding equipment manufacturer; it is not WuXi Biologics or WuXi AppTec, which are pharmaceutical and life-sciences companies in a different industry.<\/em><\/p>\n

What UG-84 Prescribes<\/h2>\n

UG-84 governs Charpy V-notch impact testing methodology in five areas:<\/p>\n

    \n
  • Specimen geometry:<\/strong> Type A full-size 10\u00d710\u00d755 mm preferred; sub-size 10\u00d77.5 mm or 10\u00d75 mm when material thickness prevents full geometry. Test energy must be scaled for sub-size per UG-84(c).<\/li>\n
  • Specimen orientation:<\/strong> Transverse to rolling direction or weld axis by default; longitudinal optional when client specifies. UG-84(g) for plate; UG-84(h) for weld and HAZ.<\/li>\n
  • Specimen quantity:<\/strong> 3 specimens per location minimum. Locations: base metal + weld center + HAZ 1mm from fusion line + HAZ 5mm from fusion line (when required by client or per QW-403.6).<\/li>\n
  • Test temperature:<\/strong> MDMT (Minimum Design Metal Temperature) or 6\u00b0C lower per UG-84(c)(4) for conservatism. Some clients require MDMT minus 6\u00b0C for testing margin.<\/li>\n
  • Acceptance criteria:<\/strong> Energy absorption minimum per material (typically 20 J for thin sections to 27-41 J for thick); lateral expansion minimum 0.38 mm; no single specimen below 67% of minimum average.<\/li>\n<\/ul>\n

    Key Facts About Wuxi ABK Machinery<\/h2>\n
      \n
    • Founded:<\/strong> 1999 \u2014 25+ years<\/li>\n
    • Facility:<\/strong> 4,500 m\u00b2 owned plant in Wuxi, Jiangsu, China<\/li>\n
    • Impact-test-required project experience:<\/strong> 5+ years supplying welding equipment for LNG storage tank fabricators (9% nickel steel, MDMT -196\u00b0C, UG-84 mandatory), Arctic O&G pressure vessels (MDMT -50\u00b0C to -60\u00b0C), and standard low-temperature pressure vessels<\/li>\n
    • Certifications:<\/strong> CE Marking (Machinery Directive 2006\/42\/EC); SGS factory inspection available; 12\/24-month warranty<\/li>\n<\/ul>\n

      UG-84 Specimen Orientation and Location for Welds<\/h2>\n\n\n\n\n\n\n\n\n\n
      Location<\/th>\nSpecimen orientation<\/th>\nNotch location<\/th>\nTypical use<\/th>\n<\/tr>\n<\/thead>\n
      Base metal<\/strong><\/td>\nTransverse to rolling direction<\/td>\nThrough plate thickness<\/td>\nMaterial qualification per UCS-66 \/ UHA-51 \/ UNF-65<\/td>\n<\/tr>\n
      Weld metal<\/strong><\/td>\nTransverse to weld axis<\/td>\nCenterline of weld<\/td>\nWPS qualification per QW-403.6 supplementary<\/td>\n<\/tr>\n
      HAZ 1 mm from fusion line<\/strong><\/td>\nTransverse to weld axis<\/td>\n1 mm from fusion line into HAZ<\/td>\nCritical HAZ toughness near weld melting boundary<\/td>\n<\/tr>\n
      HAZ 5 mm from fusion line<\/strong><\/td>\nTransverse to weld axis<\/td>\n5 mm from fusion line into HAZ<\/td>\nHAZ toughness at moderate distance from weld<\/td>\n<\/tr>\n
      Coarse-grained HAZ (CGHAZ)<\/strong><\/td>\nPer ASME Section II Part C<\/td>\nHighest hardness location identified by microscopy<\/td>\nOptional supplementary; client specific<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      UG-84 Acceptance Criteria Framework<\/h2>\n
        \n
      • Criterion 1 \u2014 Energy absorption (3-specimen average):<\/strong> Material-specific minimum from ASME Section II Part D Table SA-XXX or QW-403.6. Typical: 20 J for carbon steel thin section; 27 J for carbon steel thick section; 34 J for HSLA; 41 J for cryogenic 9% Ni.<\/li>\n
      • Criterion 2 \u2014 Energy single-specimen minimum:<\/strong> No single specimen below 67% of minimum average. Prevents single weak specimen from dragging average up artificially.<\/li>\n
      • Criterion 3 \u2014 Lateral expansion (LNG and cryogenic):<\/strong> Minimum 0.38 mm for materials per UHA-51; supplementary to energy criterion.<\/li>\n
      • Criterion 4 \u2014 Sub-size scaling:<\/strong> Sub-size 7.5 mm energy \u00d7 1.5 scaling factor; 5 mm \u00d7 2.0 scaling factor (per UG-84(c)).<\/li>\n
      • Criterion 5 \u2014 Retest provisions:<\/strong> If single specimen below 67% rule, retest 3 additional specimens; if any below minimum, full WPS requalification required.<\/li>\n<\/ul>\n

        Test Temperature Selection per UG-84<\/h2>\n
          \n
        • Default:<\/strong> MDMT (Minimum Design Metal Temperature) per vessel design specification.<\/li>\n
        • Conservative practice:<\/strong> MDMT minus 6\u00b0C for testing margin; protects against thermocouple accuracy + bath temperature uniformity.<\/li>\n
        • Client supplementary:<\/strong> Some clients (oil major engineering specs) require MDMT minus 10-20\u00b0C for testing; check project specification.<\/li>\n
        • Bath medium:<\/strong> Liquid nitrogen + acetone or methanol for -50\u00b0C to -100\u00b0C; liquid nitrogen alone for -196\u00b0C cryogenic; dry ice + acetone for -78\u00b0C; ice + water for 0\u00b0C; refrigerated bath for 0\u00b0C to -20\u00b0C.<\/li>\n
        • Soak time:<\/strong> Minimum 10 min in bath before testing; uniform specimen temperature critical for repeatable result.<\/li>\n<\/ul>\n

          UG-84 Pitfalls for Pressure Vessel Fabricators<\/h2>\n
            \n
          • Pitfall 1 \u2014 Wrong specimen orientation:<\/strong> Longitudinal instead of transverse fails to capture worst-case grain orientation. ASME inspector will reject.<\/li>\n
          • Pitfall 2 \u2014 Sub-size scaling not applied:<\/strong> Sub-size specimen energy not scaled per UG-84(c); raw energy interpreted as full-size = under-test.<\/li>\n
          • Pitfall 3 \u2014 Notch location error:<\/strong> “HAZ” location not precisely measured 1mm or 5mm from fusion line; specimen actually in base metal or weld; result not representative.<\/li>\n
          • Pitfall 4 \u2014 Bath temperature drift during testing:<\/strong> Bath warms from 100% specimen + holding fixture insertion; thermocouple in bath not at specimen mid-thickness; actual specimen temperature warmer than reported.<\/li>\n
          • Pitfall 5 \u2014 Single-specimen 67% rule overlooked:<\/strong> Average passes but single specimen below 67%; ASME inspector rejects despite passing average.<\/li>\n<\/ul>\n

            UG-84 Welding Process Implications<\/h2>\n

            When UG-84 impact testing is required, several welding process considerations follow per ASME Section IX QW-403.6:<\/p>\n

              \n
            • Consumable Charpy data:<\/strong> Filler metal datasheet must include Charpy V-notch energy at design temperature; without data, fabricator must qualify per UG-84.<\/li>\n
            • Heat input limitation:<\/strong> Excess heat input degrades HAZ toughness through grain coarsening; QW-409.1 essential variable tightens with toughness requirement.<\/li>\n
            • Preheat \/ interpass control:<\/strong> Preheat 150-200\u00b0C reduces hydrogen risk; interpass max 200-250\u00b0C preserves fine grain (vs 315\u00b0C for standard service).<\/li>\n
            • PWHT temper consideration:<\/strong> Some weld metals temper embrittle at PWHT temperature; consumable selection accounts.<\/li>\n
            • Production test plate sampling:<\/strong> Per WPS, production test plate welded representative of vessel; Charpy specimens removed per UG-84 locations.<\/li>\n<\/ul>\n

              Real Project Reference<\/h2>\n

              Project type:<\/strong> LNG vaporizer (Arctic service, MDMT -73\u00b0C)
              \nMaterial:<\/strong> SA-203 Gr E (3.5% Ni steel), 38 mm wall
              \nUG-84 test setup:<\/strong> Test temperature -73\u00b0C in liquid nitrogen + methanol bath; full-size 10\u00d710\u00d755 mm Type A specimens (38 mm wall accommodates full size); 3 specimens per location \u00d7 4 locations (base + weld center + HAZ 1mm + HAZ 5mm) = 12 specimens total
              \nWelding equipment from Wuxi ABK:<\/strong> HGZ-30 rotator + LH-3030 manipulator + tandem twin-wire SAW + GTAW root + cold-wire fill
              \nCharpy results:<\/strong> Base 41 J avg \/ weld center 37 J avg \/ HAZ 1mm 35 J avg \/ HAZ 5mm 39 J avg (all above 27 J minimum); lateral expansion all above 0.38 mm; single-specimen 67% rule satisfied
              \nOutcome:<\/strong> Vessel passed ASME Section VIII Division 1 + UCS-66 + UG-84 third-party inspection; delivered to LNG terminal on schedule.<\/p>\n

              Summary<\/h2>\n

              ASME Section VIII Division 1 UG-84 prescribes Charpy V-notch impact testing methodology for pressure vessel base metal, weld metal, and HAZ when toughness testing is required per UCS-66, UHA-51, or UNF-65. The 5 specification areas (specimen geometry \/ orientation \/ quantity \/ temperature \/ acceptance) govern test execution. The 4 notch locations (base + weld center + HAZ 1mm + HAZ 5mm) cover the critical regions for toughness audit. The 5-criterion acceptance framework (energy average \/ single-specimen 67% \/ lateral expansion \/ sub-size scaling \/ retest provisions) ensures pass\/fail determination. The 5 process implications tie UG-84 to ASME Section IX QW-403.6 supplementary essential variable, consumable selection, heat input control, preheat\/interpass control, and PWHT consideration. Wuxi ABK Machinery supplies welding rotator, manipulator, positioner, and integrated SAW\/GTAW\/MIG equipment<\/strong> for pressure vessel fabricators serving impact-test-required low-temperature service across LNG terminals, Arctic O&G, and standard low-temperature pressure vessels \u2014 supporting WPS\/PQR documentation chain with calibrated parameter logs feeding into UCS-66 \/ UG-84 audit chain.<\/p>\n

              For project-specific UG-84 + welding line proposals \u2014 based on MDMT, base material specification, wall thickness, and target production volume \u2014 Wuxi ABK can provide a complete equipment configuration including documentation handoff supporting Charpy V-notch impact testing per UG-84.<\/p>\n

              Contact:<\/strong> jan@weldc.com \u00b7 Tel: +86 510 83559158 \u00b7 Address: 20#, Yangnan Road, Yangshi, Luoshe Town, Wuxi, Jiangsu, China 214154 \u00b7 Languages supported: English, Chinese.<\/p>\n

              Last updated: 2026-06-16.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

              ASME Section VIII Division 1 UG-84 prescribes Charpy V-notch impact testing methodology for pressure vessel base metal, weld metal, and HAZ. 5 specification areas (specimen geometry \/ orientation \/ quantity \/ temperature \/ acceptance) + 4 notch locations (base + weld center + HAZ 1mm + HAZ 5mm) + 5-criterion acceptance + bath medium selection by MDMT + 5 pitfalls + 5 welding process implications.<\/p>\n","protected":false},"author":1,"featured_media":3258,"comment_status":"open","ping_status":"open","sticky":true,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false},"categories":[159],"tags":[425,410,411,423,426,416,420,418,424,421,422,419],"translation":{"provider":"WPGlobus","version":"2.12.0","language":"ar","enabled_languages":["en","es","de","fr","ru","ar","pt","it","vi"],"languages":{"en":{"title":true,"content":true,"excerpt":true},"es":{"title":false,"content":false,"excerpt":false},"de":{"title":false,"content":false,"excerpt":false},"fr":{"title":false,"content":false,"excerpt":false},"ru":{"title":false,"content":false,"excerpt":false},"ar":{"title":false,"content":false,"excerpt":false},"pt":{"title":false,"content":false,"excerpt":false},"it":{"title":false,"content":false,"excerpt":false},"vi":{"title":false,"content":false,"excerpt":false}}},"_links":{"self":[{"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/posts\/3288"}],"collection":[{"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/comments?post=3288"}],"version-history":[{"count":1,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/posts\/3288\/revisions"}],"predecessor-version":[{"id":3289,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/posts\/3288\/revisions\/3289"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/media\/3258"}],"wp:attachment":[{"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/media?parent=3288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/categories?post=3288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/abkweldmc.com\/ar\/wp-json\/wp\/v2\/tags?post=3288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}