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Destructive testing is accomplished by forcing the material to fail under various load factors. The destructive testing method is used to find mechanical properties of materials such as tensile strength, yield strength, hardness, impact toughness, elongation, etc.
The method determines the point of failure of the material. This test is carried out under severe operational circumstances, and conditions are continual till the material breaks. The method of destructive testing ensures the reliability of material or mechanical part when subjected to the load. It also identifies whether the part or device produced encompass the required properties.
Destructive Testing – Tension Test
Tension test, also known as tensile test, is associated with the mechanical test of metal products subjected to a restrained load enough to bring to the rupture. The force applied is perpendicular to the cross-sectional area of the test item. Full section specimen will be tested in a 200 mm gage (8 in.) length. Four mechanical properties are determined from tension test:
- Yield Strength
- Tensile Strength
- Elongation
- Reduction of Area
Look at the following stress-strain curve:
The vertical axis shows stress and the horizontal axis indicates strain or change in dimension or indicates the increase of the length of the cylindrical test specimen. The point 1 is the yield point, it means if you pull a steel specimen near to the point 1 (stress level) the machine will record an increase in the length but as soon as you released the load it will be returned to the original length instantly.
This point is named yield point which a material change from elastic to plastic property (in tension machine) it means if you pass this point it will not return to the original length and you will experience a permanent deformation. The stress that you need to imply to a material to reach to point 1 is the yield strength.
If you pass point 1 and continue to pulling test specimen, you will have an increase in the length, but at the same time, you need to imply more load. Ultimately, you will reach the point 2 with the maximum deformation (increase in the length of test specimen), and the test specimen will start to the necking, this is the point 2 and is named tensile strength.
Any engineered material has a certain min yield strength and tensile strength at room temperature. These values were obtained from above mentioned tests. For example, the typical pressure vessel plate SA 516 Gr 70 has a minimum yield strength of 38, 000 PSI (Point 1 in above curve) and minimum tensile strength of 70, 000 PSI (Point 2 in above curve).
These values are for testing at the room temperature; obviously, if you increase the temperature, these values will be reduced since material gets softer when subjected to the higher temperature.
The tension test machine will measure the applied load, if you divide the applied load to the cross section area, you can calculate the yield strength amount. For instance, if you have a rectangular solid bar with 1 inch x 2 inch dimension and the tension test machine records yield point load as 60,000 Ib, then your yield strength will be 60, 000 /(1 x 2) = 30, 000 psi
Similarly, the machine will calculate the tensile strength (by dividing amount of load to the cross section area)
Destructive Test – Elongation
The length between each two line in following tensile test specimen is 2 inch. After completion of the test, you can put the separated part together and measure the length between two lines. As you see, the length after the test is 2.5 inch. It means your elongation of this test was (2.5-2.0)/2.0 = 25%
Similarly, you can calculate “reduction in area” percentage by A1-A2/ A1. The A1 is the cross section area before the test, and the A2 is the broken surface area.
Both elongation and reduction in area values indicate the degree of ductility and machinability.
Bend Test
The qualitative ductility of material is determined by using bend test. In bend test, the specimen is bent over a specified diameter to a specified angle for a specific amount of time. After bending, the stressed side of bend test specimen is checked and verified.
If no crack observed it indicates that the material had a good ductility, propagation a major crack on the bent side shows that the material lacked adequate ductility. The ASTM E290 provides the test procedure for bend test.
Impact Test
Why are we doing impact test? The material property changes from ductile to brittle in the certain temperature, as you decrease your services temperature, your ductility will be decreased, and your tensile strength will be increased. Reduction in ductility means your risk for brittle fracture will be higher.
If you drop a plain carbon steel 10 in. by 10 in. Plate from 6 feets height to concrete floor, you will only hear an impact noise and nothing more, but if you place this plate in laboratory freezer and cooled it down to the -100 degree F and then drop it, probably it will hit the floor and breaks to the several pieces.
We are doing impact test, to make sure our material will be safe in the minimum metal design temperature. One of the most common impact tests is a notched bar impact test called the Charpy impact test.
The Charpy impact test is a destructive test and uses a pendulum-type single-blow impact test where the specimen is secured at both ends and will be break by a falling pendulum. The energy absorbed, as determined by the subsequent rise of the pendulum, is a measure of the impact strength or notch toughness of material. The tests results are usually recorded in foot-pounds.
Look at the following picture, the pendulum hits the test specimen (the test specimen removed from freezer just before the test) and breaks it and rises, if rises remarkably, it indicates that the test specimen received a little energy to break it. In the same test, if rises a little, it shows that the pendulum spent lots of energy to break the test specimen.
ASTM A370 provides procedure and direction for conducting destructive testing. In some cases, refers you to different ASTM standards.
Return to Industrial Inspection
Executive Summary & Industrial Inspection Scope
In demanding industrial environments across Oil, Gas, Petrochemical, Offshore, and Heavy Process Infrastructure, rigorous compliance with ASME Section IX, AWS D1.1, EN ISO 15614 is essential to ensure operational integrity, personnel safety, and compliance with statutory regulatory frameworks. This technical specification provides QA/QC managers, procurement engineers, welding inspectors, and third-party inspection (TPI) agencies with an authoritative, field-tested guideline for “What Is The Destructive Testing”.
Ensuring compliance regarding what is the destructive testing minimizes the risk of catastrophic asset failures, costly unscheduled shutdowns, and supplier non-conformances. The following technical sections delineate the scope of inspection, mandatory verification protocols, acceptance criteria, documentation deliverables, and root cause mitigation strategies.
Governing International Engineering Codes & Specifications
Verification and validation of What Is The Destructive Testing must strictly conform to the latest editions of the following international engineering codes and project specifications:
• **Primary Standard Reference:** ASME Section IX, AWS D1.1, EN ISO 15614
• **Quality Management & Inspection Systems:** ISO 9001:2015 & ISO/IEC 17020 (Requirements for the operation of various types of bodies performing inspection)
• **Material Compliance & Traceability:** EN 10204 Type 3.1 / 3.2 Inspection Certificates for metallic and non-metallic pressure-retaining components
• **Personnel Qualification:** ASNT SNT-TC-1A / ISO 9712 for NDT personnel, CSWIP 3.1 / AWS CWI for welding inspection, and NACE / AMPP Level 2/3 for coating and corrosion personnel
• **Statutory & Health Safety Directives:** ASME Boiler & Pressure Vessel Code (BPVC), API Standards, OSHA, and regional local authority regulations.
Step-by-Step Quality Control & Inspection Procedure
The execution of quality surveillance for What Is The Destructive Testing is structured across four progressive QA/QC intervention phases:
Stage 1: Pre-Inspection & Engineering Document Review (Review Point – R)
Prior to commencement of any physical activities or manufacturing operations related to What Is The Destructive Testing, the contractor or vendor must submit all technical submittals to the Owner or TPI agency for formal review and approval.
- Verification of approved Inspection and Test Plan (ITP) identifying all Hold (H), Witness (W), Review (R), and Surveillance (S) intervention points.
- Cross-examination of Material Test Reports (MTR / Mill Certificates) against standard design specifications (ASME Section IX, AWS D1.1, EN ISO 15614).
- Review and approval of specific Procedure Qualification Records (PQR), Welding Procedure Specifications (WPS), or calibration certificates.
- Verification that all measurement instruments, gauges, and NDT equipment hold valid calibration certificates from ISO/IEC 17025 accredited calibration laboratories (within 6 to 12 months validity).
Stage 2: In-Process Witnessing & Fabrication Control (Witness / Hold Point – W/H)
During the active execution phase, the certified inspector performs physical surveillance to ensure strict adherence to certified drawings, manufacturing procedures, and code tolerances.
- Verification of material traceability (heat number, heat treatment lot, plate number) transferred accurately onto fabricated components.
- Dimensional verification and visual inspection using calibrated gauges, micrometer depth dials, or laser alignment systems.
- Monitoring ambient environmental parameters (relative humidity, dew point, substrate temperature) when applying surface treatments, welding preheat, or pressure testing.
- Witnessing non-destructive examination (RT, UT, MT, PT, PMI) at specified percentages according to project critical rating and code requirements.
Stage 3: Final Acceptance, Pressure/Performance Testing & Marking (Hold Point – H)
The culminating milestone where the fully assembled or completed item is subjected to definitive acceptance tests in the presence of the Owner’s Third-Party Inspector (TPI).
- Execution of pressure proof tests (Hydrostatic at 1.3x to 1.5x MAWP or Pneumatic test) with dual calibrated pressure gauges and temperature recorders.
- Full visual inspection of completed surfaces, welds, protective coatings, and flange contact faces for absence of mechanical damage or code defects.
- Validation of permanent stamping, low-stress die markings, nameplate data verification, and barcoding in strict conformity with project specs.
- Clearing all open punch-list items, non-conformance reports (NCRs), and concession requests prior to issuance of the release note.
Stage 4: Packing, Preservation & Inspection Release (Inspection Release Certificate – IRC)
Ensuring the inspected equipment is adequately protected against atmospheric corrosion, mechanical shock, and marine transit degradation.
- Inspection of rust preventative coatings, desiccant bags, flange face blind protectors, and vapor corrosion inhibitor (VCI) packaging.
- Verification of heavy-lift sea fastening lugs, center-of-gravity markings, and export crating compliance (ISPM 15 wooden crating).
- Compilation and signing of the final Inspection Release Certificate (IRC / Shipping Release) and manufacturer data dossier (MDR).
Technical Acceptance Criteria & Tolerances Matrix
All measurements and physical characteristics must comply with the engineering tolerances and acceptance thresholds tabulated below:
| Welding Variable / Test Item | Governing Code (ASME Sec IX / AWS) | Permissible Tolerance / Requirement | Test Method / Verification | QC Intervention |
|---|---|---|---|---|
| P-Number & Group Number Verification | ASME Sec IX QW-420 | Base metal must strictly match qualified P-Number/Group Number on PQR | MTR Chemical Analysis & Positive Material Identification (PMI) | Review (R) |
| F-Number & A-Number Filler Metal Control | ASME Sec IX QW-430 & QW-440 | Filler rod/wire must match certified AWS classification with heat/lot batch certs | Batch Test Certificate & Oven Storage Temperature Check (>120°C) | Witness (W) |
| WPS Essential Variables Tolerances | ASME Sec IX QW-250 to QW-265 | Current/Voltage ±10%, Travel speed ±10%, Heat input within qualified maximum J/mm | Calibrated Digital Clamp Meter & Heat Input Calculation | Surveillance (S) |
| Preheat & Interpass Temperature | ASME Sec IX / ASME B31.3 | Preheat maintained at min specified temp 75mm on each side; max interpass not exceeded | Tempilstik (Temperature crayon) / Calibrated Contact Pyrometer | Witness (W) |
| Post-Weld Heat Treatment (PWHT) | ASME Sec VIII Div 1 UCS-56 | Heating rate, soaking time (1 hr per 25mm), and cooling rate within strict code graph | Thermocouple placement & Multi-channel Temperature Recorder Chart | Hold (H) |
| Tensile & Guided Bend Mechanical Tests | ASME Sec IX QW-150 / QW-160 | Tensile strength not lower than base metal min specified; bend specimens: zero open flaw >3.2mm | Destructive Lab Testing (Accredited ISO 17025 Lab) | Hold (H) |
Mandatory QA/QC Dossier & Inspection Deliverables
Prior to the final issuance of the Inspection Release Certificate (IRC), the contractor and vendor must compile and submit the verified manufacturer data record containing:
- Approved Inspection & Test Plan (ITP) with sign-off stamps by Contractor, Client, and TPI.
- Material Test Reports (MTR / Mill Test Certificates EN 10204 Type 3.1 or 3.2).
- Certified Welding Procedure Specifications (WPS), Procedure Qualification Records (PQR), and Welder Performance Qualifications (WPQ).
- Calibration Certificates for all test instruments and measuring equipment (NABL / ISO 17025 accredited).
- Non-Destructive Examination Reports (RT, UT, MT, PT, PMI, Ferrite Content) evaluated by Level II/III inspectors.
- Heat Treatment & PWHT Time-Temperature Recorder Charts with thermocouple layout drawings.
- Hydrostatic / Pneumatic Pressure Proof Test Certificate with calibrated chart recorder logs.
- Surface Preparation and Protective Coating Inspection Reports (Daily environmental log, blast profile, DFT summary).
- Non-Conformance Report (NCR) and Concession Disposition Closeout Log.
- Official Inspection Release Certificate (IRC / Shipping Release Note) permitting packing and dispatch.
Common Non-Conformances & Field Mitigation Strategies
Based on extensive third-party inspection field records in oil & gas projects, the following deviations require heightened surveillance:
Defect / Hazard: Material Grade Substitution & Lack of Heat Traceability
Root Cause: Uncontrolled workshop storage, missing color coding, or unverified supplier sub-tier procurement without EN 10204 3.1 documentation.
Preventative Action: Enforce strict 100% Positive Material Identification (PMI) prior to cutting, and mandatory material receiving inspection with physical stamping cross-referenced to original mill test certificates.
Defect / Hazard: Out-of-Tolerance Fit-Up & Alignment Mismatch
Root Cause: Poor thermal cutting, thermal distortion from excessive preheat, or inadequate jigging and tacking arrangements.
Preventative Action: Establish a mandatory Witness/Hold point at joint fit-up before root pass deposition. Use calibrated Hi-Lo gauges to verify bevel angle, root face, and root gap according to the qualified WPS.
Defect / Hazard: Premature Coating Delamination & Blistering Under Film
Root Cause: Excessive soluble salt contamination (>20 mg/m²) left on the substrate, blast cleaning below dew point (<3°C above dew point), or oil/moisture in the blasting compressor air line.
Preventative Action: Perform Blotter Test (ASTM D4285) daily on compressed air, enforce Bresle patch chloride testing, and apply primer within 4 hours of abrasive blasting before rust blooming initiates.
Defect / Hazard: Pressure Drop During Final Hydrostatic Proof Testing
Root Cause: Micro-leakage through temporary test flange gaskets, entrapped air pockets inside vessel high points, or inadequate temperature stabilization.
Preventative Action: Ensure thorough venting at all high-point vents until bubble-free fluid emerges, allow minimum 15-minute temperature stabilization between filling medium and ambient metal, and torque all blind flanges with calibrated torque wrenches.
Frequently Asked Questions (FAQ)
Q: What are the mandatory qualifications for inspectors verifying What Is The Destructive Testing?
A: Inspectors must hold recognized international certifications applicable to the discipline. For welding and fabrication: CSWIP 3.1/3.2, AWS CWI, or API 510/570 Source Inspector. For NDT: ISO 9712 or ASNT SNT-TC-1A Level II minimum. For coatings: NACE / AMPP Level 2 or FROSIO Level III. Additionally, the inspection agency must operate under an ISO/IEC 17020 accredited quality management system.
Q: How does PtroTek resolve non-conformances (NCRs) encountered during vendor surveillance?
A: When a deviation from certified drawings or ASME Section IX, AWS D1.1, EN ISO 15614 is detected, the inspector issues a formal Non-Conformance Report (NCR) within 24 hours. The vendor must submit a Root Cause Analysis (RCA) and proposed disposition (Rework, Repair, or Concession). Work on the affected component is halted (Hold Point) until the Owner’s engineering authority approves the disposition and a re-inspection confirms full compliance.
Q: What is the difference between Witness (W) and Hold (H) points in an Inspection & Test Plan (ITP)?
A: A Hold Point (H) is a mandatory milestone where fabrication or testing CANNOT proceed without the physical presence of the designated client or third-party inspector. Written clearance or stamping is strictly required. A Witness Point (W) requires prior notification (typically 24 to 48 hours) to the inspector; however, if the inspector fails to attend at the scheduled time, fabrication or testing may proceed with subsequent review of the test records.
Q: Can international clients review inspection reports and photos in real time?
A: Yes. PtroTek provides comprehensive Flash Reports issued within 24 hours of inspection completion, followed by detailed formal inspection reports accompanied by high-resolution calibrated photographic evidence, dimension logs, and signed vendor test records for complete global transparency.
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