Magnetic Particle Testing of Welds — D1.1:2025 Requirements
वेल्डिंग का चुंबकीय कण परीक्षण AWS D1.1:2025 खंड 8.10 द्वारा नियंत्रित होता है, जिसमें तालिका 8.1 के अनुसार स्वीकृति, खंड 8.14.4 के अनुसार अनिवार्य ASTM E3024/E3024M प्रक्रिया, और खंड 8.14.6 के अनुसार NDT लेवल II कर्मियों का प्रमाणीकरण शामिल है — UT की तरह, MT तभी लागू होता है जब अनुबंध दस्तावेज़ इसे निर्दिष्ट करते हैं।
वेल्ड पर एमटी क्या पता लगाता है
Magnetic particle testing reveals surface and slightly subsurface discontinuities in ferromagnetic materials — carbon steel, low-alloy steel, ferritic stainless — that are too small, too tight, or too oriented to find by दृश्य निरीक्षण alone. The method magnetizes the test area and applies fine ferromagnetic particles to the surface; at any असंतति that interrupts the magnetic flux path, the leaked flux holds the particles in a visible indication.
Practical detection depth depends on the magnetizing technique, current type, and material permeability, but typical surface-and-near-surface coverage is on the order of a few millimeters from the surface. Tight, surface-breaking दरारें — including hot cracks, hydrogen cracks at the toe of fillet welds, lamellar tears in T-joints — are the classic MT targets in वेल्डिंग निरीक्षण.
MT does not work on austenitic stainless steel, aluminum, copper, brass, or other non-ferromagnetic materials. For those, use liquid पेनेट्रेंट testing (PT) per Clause 8.14.5.
D1.1 खंड 8 में एमटी कहाँ स्थित है
AWS D1.1:2025 चुंबकीय कण परीक्षण को खंड 8 (स्वीकृति मानदंड) के भाग C के भीतर Clause 8.10 के तहत प्रवेशक परीक्षण (PT) के साथ संयुक्त रूप से रखता है। एमटी के लिए प्रक्रिया विशेष रूप से भाग D (प्रक्रियाएं) में Clause 8.14.4 के तहत रहती है। एमटी सहित किसी भी NDT विधि के लिए कर्मियों की योग्यता Clause 8.14.6 में रहती है।
खंड 8.10 के अनुसार शब्दशः: "वेल्ड्स जो एमटी या पीटी के अधीन हैं, उन्हें 8.10.1 में स्वीकृति मानदंडों के आधार पर मूल्यांकन किया जाएगा। परीक्षण 8.14.4 या 8.14.5 के अनुरूप किया जाएगा, जो भी लागू हो।" तो खंड 8.10 स्वीकृति पक्ष स्थापित करता है; खंड 8.14.4 प्रक्रियात्मक पक्ष स्थापित करता है; साथ में वे D1.1 के तहत वेल्ड पर पूर्ण एमटी आवश्यकता को परिभाषित करते हैं।
एमटी कब आवश्यक है
Per the framing of Clause 8.6.4 (Specified NDT Other than दृश्य), NDT — including चुंबकीय कण testing — is specified by the contract documents furnished to bidders. There is no general blanket D1.1 requirement that all welds be MT-tested. The Engineer determines on each project whether MT is required, on which welds, at what stage, and to what स्वीकृति level.
वेल्ड पर एमटी के लिए सामान्य परियोजना विनिर्देशों में शामिल हैं: अंतिम पास द्वारा कवर किए जाने से पहले टैक वेल्ड, महत्वपूर्ण सीजेपी ग्रूव वेल्ड में रूट पास, मरम्मत उत्खनन जो फिर से वेल्ड किए जाने वाले हैं, गतिशील रूप से
Per Clause 8.6.5, if NDT other than visual is not in the original contract but is later requested by the Owner, the Owner is responsible for the associated costs unless the testing reveals an attempt to defraud or gross nonconformance to the संहिता — in which case the मरम्मत work is at the contractor's expense.
एमटी प्रक्रिया: एएसटीएम E3024 (अनिवार्य) और एएसटीएम E709 (सूचनात्मक)
Per Clause 8.14.4 verbatim: "When MT is used, the procedure and technique shall be in conformance with ASTM E3024/E3024M, and the मानक of acceptance shall be in conformance with Clause 8, Part C, of this code." So D1.1:2025 mandates ASTM E3024/E3024M for the procedure.
The older ASTM E709 ("Standard गाइड for Magnetic Particle Testing") is referenced only in Commentary C-8.14.4 as informational guidance: "ASTM E709 is a standard guide and may be used for information in conjunction with E3024/E3024M." This is a common practitioner confusion — E709 is widely cited in older project specifications and shop documents, but the current D1.1:2025 mandatory reference is E3024/E3024M, not E709.
“If your project spec still cites ASTM E709 as the mandatory MT procedure for D1.1 work, that spec was written against an older edition of the code. D1.1:2025 Clause 8.14.4 mandates E3024/E3024M; E709 is informational only per Commentary C-8.14.4.”
D1.1:2025 Clause 8.14.4 + Commentary C-8.14.4
सामान्य एमटी तकनीकें
Within the E3024 procedure, several techniques are typical for वेल्ड निरीक्षण:
- Yoke method (AC or DC) — most common for field weld inspection. A handheld electromagnetic yoke applies a magnetic field across two contact points. Portable, fast, no risk of arc strikes on the part. The dominant technique for in-place MT on structural welds.
- Prod method — current is passed through the part via two इलेक्ट्रोड prods. High sensitivity but historically associated with arc-strike risk at the prod contact points; many specifications restrict or prohibit prods on critical members.
- Wet continuous — particles suspended in a fluid carrier are applied while the magnetizing current is on. Highest sensitivity, used for shop-controlled inspection of critical components; less practical for field use.
- Dry continuous — dry particles dusted on the surface during magnetization. Common with yoke testing for field work where wet bath handling is impractical.
निरीक्षक योग्यता
Per Clause 8.14.6.1, NDT personnel performing testing other than visual shall be certified as NDT Level II in the test method and technique, or as NDT Level I working under the supervision of an NDT Level II. The Level II inspector interprets indications, evaluates them against acceptance criteria, and signs off on the inspection record.
Per Clause 8.14.6.2, employer-based certification follows either ASNT SNT-TC-1A Recommended Practice or ANSI/ASNT CP-189. Certification of Level I and II individuals shall be performed by a Level III. Per Clause 8.14.6.3, third-party certification options include the ASNT Central Certification Program (ACCP), ASNT CP-9712, CAN/CGSB-48.9712, and ISO 9712. Per Clause 8.14.6.5, NDT personnel performing inspections under 8.14.6 are exempted from the AWS QC1 (CWI) आवश्यकताएँ — an MT inspector does not need a CWI to perform MT on a D1.1 job, though many do hold both credentials.
CWI बनाम ASNT क्रेडेंशियल्स के लिए, CWI बनाम ASNT Level 2 संदर्भ देखें।
एमटी बनाम पीटी बनाम यूटी — निर्णय मैट्रिक्स
| Factor | MT (Clause 8.10 / 8.14.4) | PT (Clause 8.10 / 8.14.5) | UT (Clause 8.15) |
|---|---|---|---|
| Detection | Surface + slightly subsurface | Surface only (open to surface) | Volumetric (full मोटाई) |
| Material | Ferromagnetic only | Any non-porous material | Any solid material |
| Speed | Fast (yoke 30-60 s/joint) | Slower (5-30 min cycle: clean/penetrant/dwell/developer) | Moderate (depends on weld length) |
| Equipment | Yoke or prod, particles | Penetrant + cleaner + developer | UT instrument + transducer + couplant |
| Procedure ref | ASTM E3024/E3024M per 8.14.4 | ASTM E165/E165M per 8.14.5 | Per Clause 8.15 + Annex H for PAUT |
| Acceptance ref | Table 8.1 per 8.10.1 | Table 8.1 per 8.10.1 | Tables 8.2, 8.3 per Clause 8.15 |
| Inspector | NDT MT Level II | NDT PT Level II | NDT UT Level II (+ 320 hr for PAUT) |
| Best fit | Cracks at fillet toes, repair-excavation verification, ferritic structural welds | Surface cracks on stainless or aluminum, leak-tight surface verification | Internal flaws in CJP groove welds, thick sections |
एमटी स्वीकृति मानदंड (खंड 8.10.1)
Per Clause 8.10.1: "All MT and PT indications shall meet the acceptance requirements of तालिका 8.1." So the MT inspector applies the same Table 8.1 criteria used for visual inspection — with two key classification rules added by Clause 8.10.1:
- Linear discontinuity: defined as one whose length exceeds three times its width. Per 8.10.1(1), linear discontinuities shall be considered equal to the आकार and shape of the indication itself.
- Rounded discontinuity: defined as one whose length is three times its width or less. May be round or irregular and may have tails. Per 8.10.1(2), prior to interpretation, the medium (particles for MT, developer for PT) shall be removed for accurate measurement.
Per Clause 8.10.2, the finishing of surfaces to improve detectability of discontinuities using MT or PT is permitted, provided the operation conforms to Clause 7. This is how shops legitimately grind weld toes or surfaces to remove visual obstructions before MT — subject to Clause 7 सीमाएँ on grinding into आधार धातु or weld throat.
Per Clause 8.11.1 (Time of Testing), MT may begin immediately after the completed welds have cooled to ambient तापमान — with one critical exception: ASTM A514, A517, and A709 Grade HPS 100W [690W] steels require NDT to be performed not less than 48 hours after weld completion, to allow delayed (hydrogen-induced) cracking time to develop before inspection.
संबंधित मानक मार्गदर्शिकाएँ
अक्सर पूछे जाने वाले प्रश्न
Per D1.1:2025 Clause 8.10, magnetic particle testing (MT) is one of the nondestructive testing methods recognized for weld examination. As with ultrasonic testing under Clause 8.15, MT is required only when specified in the contract documents — it is not automatic for all welds. Common project specifications require MT on tack welds, root passes in critical CJP groove welds, repair excavations, and fillet welds in dynamically loaded connections. The Engineer determines when MT is required for each project.
MT reveals surface and slightly subsurface (typically up to about 3 mm depth, depending on technique and material permeability) discontinuities in ferromagnetic materials. The method makes tight, surface-breaking cracks visible by attracting magnetic particles to flux leakage at the discontinuity — many of which are too small or tightly closed for visual detection. MT does not work on austenitic stainless steel, aluminum, copper, or other non-ferromagnetic materials; for those, use liquid penetrant testing (PT).
Both detect surface-breaking discontinuities, but the underlying physics differs. Magnetic particle testing (MT) magnetizes the part and reveals flux leakage at discontinuities — it works only on ferromagnetic materials (carbon steel, low-alloy steel, ferritic stainless) and detects both surface and slightly subsurface flaws. Liquid penetrant testing (PT) draws penetrant fluid into surface-open discontinuities by capillary action, then a developer pulls the penetrant back to the surface for visualization — PT works on any non-porous material (including aluminum and austenitic stainless) but only finds surface-breaking flaws. PT takes longer per joint than MT and contaminates the work area.
Per D1.1:2025 Clause 8.14.6.1, NDT personnel must be certified as NDT Level II (or NDT Level I working under the supervision of an NDT Level II) in the specific test method and technique. Per Clause 8.14.6.2, employer-based certification follows either ASNT Recommended Practice SNT-TC-1A or ANSI/ASNT CP-189, with Level III personnel certifying Level I and II individuals. Per Clause 8.14.6.3, third-party certification may be obtained through ACCP, ASNT CP-9712, CGSB-48.9712, or ISO 9712. NDT personnel performing inspections under Clause 8.14.6 are exempted from AWS QC1 (CWI) requirements per Clause 8.14.6.5.
Yes. Per D1.1:2025 Clause 8.10.1, all MT and PT indications shall meet the acceptance requirements of Table 8.1 (visual inspection acceptance criteria). Discontinuities other than cracks shall be evaluated as either linear (length exceeds three times width) or rounded (length equals or is less than three times width). Linear discontinuities shall be considered equal to the size and shape of the indication. The MT procedure itself shall conform to ASTM E3024/E3024M per Clause 8.14.4 (ASTM E709 is referenced only as informational guidance in Commentary C-8.14.4 and is NOT mandatory).