The Piping Inspection article provides you with information about the inspection of piping and piping testing in a construction site, as well as in operating plants.
What is the definition of a pipe?
Based on API Code, the definition of pipe is a pressure-tight cylinder used to convey a fluid or to transmit a fluid pressure.
If you look to the refinery or chemical plant, you can see the jungle of pipes which are connecting the vessels together. Statistic shows that 40 % of total mechanical failures in the units are because of the process piping.
This article provides you information about site inspection of process piping as well as important points on in-service inspection in process plants.
What is the Process Piping Inspection Requirements at the Construction Site?
The construction code for process piping is ASME B31.3 Code and it covers the minimum requirements for design, materials, fabrication, inspection, testing, and commissioning.
With the above explanation, your inspection and test plan (ITP) for process piping needs to meet the requirements of ASME B31.3 Code.
ASME B31.3 refers you to the other ASME code sections for some activities. For example for welding refer to the ASME Code Section IX, pipe fitting design and selection to the ASME B16.5 and for Nondestructive testing to ASME Code Section V.
The process piping design and construction is not under the ASME Code scheme of stamped items.
It means there is not certification for construction contractors by ASME, and it is the responsibility of owner to select a qualified and experienced contractor for its process piping construction project.
This is the reason that in the ASME B31.3 code you cannot see the wording of “Authorized Inspector,” and instead the words “owner inspector” have been used.
The owner inspector can be the owner’s own qualified inspector or the inspector of a third party inspection company under contract with the owner.
Throughout the ASME Construction codes, when you see the words “authorized inspector,” you notice there is an ASME Stamp scheme there.
Contrary to the ASME B31.3, the ASME B31.1 code for power piping (boiler external piping) have the ASME stamp scheme. The construction contractor must be certified by the ASME organization and must hold the “PP” stamp.
So the wording for inspector in the ASME B31.1 is “authorized inspector,” which means that this person has specific qualifications and a commission card from NBIC.
For more details, review the Pressure Vessel Certification article. The certification process for the power piping contractor is similar to the pressure vessel.
The detail of inspection requirement in the construction field is addressed in the process piping inspection and test plan.
What is In-Service Inspection Requirement for Process Piping?
The In-Service Inspection code for your process piping is API STD 570.
The title of the code is Piping Inspection Code: In-service Inspection, Rating, Repair, and Alteration of Piping Systems.
The other API recommendation practices and codes are also necessary to be used in conjunction with this Code.
Some of these Recommend Practices are:
- API RP 574 Inspection Practices for Piping System Components,
- API RP 577 Welding Inspection and Metallurgy,
- API RP 571 Damage Mechanism Affecting Fixed Equipment in the Refining Industry,
- API 578 Material Verification Program for New and Existing Alloy Piping Systems
ASME construction and referenced code sections also might be used such as ASME B31.3 and ASME Code Section IX.
For repair, the requirement of API STD 570, or ASME PCC-2 need to be met.
The title of ASME-PCC-2, which was first published in 2006 is: “Repair of Pressure Equipment and Piping.”
The API 570 Piping Inspectors are qualified persons to do the piping system inspection.
What are the Important Items in the Piping Inspection?
These are only important points or a summary of points for the process piping in-service inspection and should not be assumed as the entire piping inspection procedure.
A piping inspection procedure is a comprehensive document, which need to cover inspection methods to be employed, equipment and material to be used, qualification of inspection personnel involved and the sequence of the inspection activities at the minimum.
You may use the following content as a summary of points for the in-service inspection of the piping system.
- Creating a piping inventory list indicating the line number, pipe specification class, rating, schedule, pipe origin location (from) and pipe destination location (to)
- Creating piping isometric sketches to facilitate inspection and the recording of corrosion monitoring locations (CMLs)
- Dividing whole unit piping into piping circuits based on process condition and potential degradation mechanism
- Selecting appropriate NDE techniques for each piping circuit based on the circuit damage mechanism
- Determination of CMLs points in piping isometric sketches based on the potential for general or localized corrosion and service specific damage mechanisms
- Determination of piping service class based consequence of failure and instruction stated in API 570 or based on the Risk Based Inspection method.
- Carry out external inspection for corrosion, leaks, previous temporary repairs, clamps, coating breakdown, insulation damage, vibration, misalignment, pipe support deterioration specifically in touch points and to air to soil interface, pipe hanger distortion or breakage and frizz damage
- External thickness measurement on CMLs on each piping circuit
- Corrosion rate calculation based on metal loss in a specific time interval
- Retirement thickness calculation based on the minmium required thickness and minimum required structural thickness
- Remaining life calculation based on the available thickness for corrosion and the corrosion rate value
- Determination of piping circuit inspection interval based remaining life calculation and piping service class
- Determination of piping inspection interval for non-thinning damage mechanism
- Making supplementary inspection with the proper NDE method for piping circuits susceptible to creep cracking
- Making supplementary inspection with the proper NDE method for piping circuits susceptible to the creep cracking
- Making supplementary inspection with the proper NDE method for piping circuits susceptible to environmental cracking from Chloride SCC, Polythionic acid SCC, Caustic SCC, Amine SCC, Carbonate SCC, Hydrogen blistering and hydrogen induced cracking (HIC), etc.
- Application of other NDE methods if it is necessary:
- PEC (pulsed eddy current), LRUT (long range UT), LREM (long range electromagnetics), RT for wall thickness loss, and CUI and neutron backscatter and infra-red thermography for detection of wet insulation
- MT (magnetic particle), WFMT (wet fluorescent magnetic particle), PT (penetrant testing), EC (eddy current), UT shear wave, AUT (automated UT), TOFD (time of flight diffraction), RT, ACFM (alternating current field measurement), AET (acoustic emission) for investigating cracking
- Thermography for detection of fouling and hot spots
- Internal inspection in opened flanges for deposition, corrosion, localized corrosion, erosion, etc.
- Internal inspection of clad or lined piping for disbanding, bulging and cracking
- Internal inspection of refractory lined piping for erosion, deterioration of anchors, undercutting of refractory and coke build up behind refractory
- Flange joint inspection for distortion and leakage and flange face inspection, ring groove and gasket for corrosion, erosion , cracking and mechanical damage
- Internal inspection of dismantled valve for corrosion, erosion, mechanical damage and cracking
- Specific attention and internal inspection of critical check valves
- Inspection of injection points for localized corrosion
- Inspection of dead legs for corrosion
- Corrosion under insulation inspection of piping in susceptible temperature (-12˚ to 175˚ C) either by advance NDT or by removal of insulation and making visual inspection
- Making appropriate reporting and report keeping and implement proper system for quick access to the records
Executive Summary & Industrial Inspection Scope
In demanding industrial environments across Oil, Gas, Petrochemical, Offshore, and Heavy Process Infrastructure, rigorous compliance with ISO 9001 / ASME / API 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 “Piping Inspection”.
Ensuring compliance regarding piping inspection 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 Piping Inspection must strictly conform to the latest editions of the following international engineering codes and project specifications:
• **Primary Standard Reference:** ISO 9001 / ASME / API
• **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 Piping Inspection 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 Piping Inspection, 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 (ISO 9001 / ASME / API).
- 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:
| Inspection Parameter / Test Item | Applicable Standard & Clause | Permissible Tolerance / Acceptance Limit | Verification Method | Intervention Type |
|---|---|---|---|---|
| Material Chemical & Mechanical Verification | ISO 9001 / ASME / API / EN 10204 3.1 | 100% compliance with minimum tensile, yield, elongation, and impact values (Charpy V-Notch at design temp) | Optical Emission Spectrometry (OES) / MTR Verification | Review (R) |
| Visual & Dimensional Tolerances | ISO 9001 / ASME / API / Project Specs | Zero cracks, lack of fusion, severe pitting; dimensional tolerances within ±1.0mm to ±3.0mm per code drawings | Calibrated Vernier, Bridge Cam, Depth Micrometer | Witness (W) |
| Non-Destructive Examination (NDT) | ASME Sec V / ASNT SNT-TC-1A | 100% compliant with code acceptance criteria; zero planar defects or unpermitted volumetric indications | Radiographic (RT) / Ultrasonic (UT) / Magnetic Particle (MT) | Hold (H) |
| Pressure / Proof Testing (Hydrostatic) | ISO 9001 / ASME / API / ASME Sec VIII | Test pressure maintained for minimum 30 to 60 mins; zero pressure drop, zero leakage or visible sweating | Dual calibrated Bourdon pressure gauges + Chart Recorder | Hold (H) |
| Surface Prep & Protective Coating Quality | SSPC-SP / NACE / ISO 8501 | Surface profile 50 – 75 µm; Dry Film Thickness (DFT) within 80/20 rule of specified nominal thickness | Replica Tape (ASTM D4417) & Magnetic Gauge (SSPC-PA 2) | Witness (W) |
| Nameplate & Final Preservation Verification | API / ASME / Client Specs | 316L SS nameplate securely affixed with correct design code, MAWP, design temp, and national board stamping | Physical visual check & VCI preservation verification | 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 Piping Inspection?
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 ISO 9001 / ASME / API 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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