What Is PSTT Inspection?
PSTT is a periodic inspection application route using advanced technology under specified conditions. Its purpose is to establish an appropriate inspection approach for eligible equipment while maintaining the required safety and regulatory assessment. PSTT is not a single test or a standard package of inspection methods. The required evidence depends on the equipment category, operating history, credible damage mechanisms and inspection plan. Completing an ultrasonic scan alone does not establish eligibility or approval. The application process involves document review by the relevant DOSH division and document review and physical inspection by the state DOSH officer or licensed person, as applicable.Which Equipment Categories Does the Guideline Cover?
The 2026 guideline separates its scope into four parts:- Part A: Pressure vessels.
- Part B: Steam boilers.
- Part C: Pressure vessels containing LPG and specified cryogenic vessels.
- Part D: Pressure vessels with special media, including lethal substances, internal media with prolonged lifespan and petroleum products.
Application Timing and Certificate Validity
For applications under Parts A, B and D, the guideline specifies submission six months before the Certificate of Fitness expires. Early preparation is therefore essential, particularly where historical thickness readings, engineering calculations or operating records must be assembled. The guideline states a Certificate of Fitness validity period of 15 months from the periodic inspection date. PSTT should not be presented as an automatic extension to a longer certificate period. Parts A and B also state that PSTT cannot be applied for two consecutive periodic inspections. Owners should check the provisions of their specific category rather than assume that the same inspection route can be repeated indefinitely. For assistance with the wider renewal process, visit our CF renewal support service.Pressure Vessel Eligibility: Corrosion Rate and Equipment Life
Part A distinguishes between newly registered vessels approaching their first periodic inspection and registered vessels that have previously undergone an internal periodic inspection. Its eligibility conditions include:- A corrosion rate of less than 0.125 mm per year, using the expected or measured corrosion rate according to the category.
- An equipment life exceeding 10 years.
- Shell operating temperature within the specified material-related creep temperature limitation referenced to API 579-1/ASME FFS-1.
- Maintenance of safety critical elements, particularly essential fittings, according to the applicable standard or manufacturer's manual.
- No dangerous occurrence affecting the vessel's integrity.
Why Damage Mechanisms Must Guide the Inspection Plan
A useful inspection plan starts with the damage that could realistically affect the equipment. Uniform thinning, localised corrosion and cracking require different inspection approaches and coverage. For pressure vessel applications, the guideline requires identification of damage mechanisms and risk category, followed by an inspection strategy covering the scope and type of examination. Our API 580 Risk Based Inspection service can support risk-based inspection planning. The methodology and proposed inspection strategy must still satisfy the requirements applicable to the PSTT application.What Should the Scheme of Examination Include?
The Scheme of Examination, or SOE, identifies the examination locations and NDT methods proposed for the vessel. It should connect the damage assessment to practical inspection activities. An effective SOE makes clear which areas will be examined, why they were selected, what coverage is proposed and how the selected methods address the expected damage. Reports should then demonstrate that the inspection followed the agreed SOE. Clear location references, traceable readings and recorded coverage help reviewers understand the findings and any limitations.Inspection Methods That Can Support the Technical Assessment
Appendix 1 provides an example pressure vessel inspection strategy covering external visual inspection, ultrasonic measurements at condition monitoring locations, ultrasonic corrosion scanning, profile radiography and shear-wave ultrasonic examination. The example varies coverage with risk ranking and damage type. Its percentages should not be treated as a universal inspection package for every vessel.Ultrasonic Thickness Inspection UTTM
Thickness measurements help assess wall loss at identified locations. Repeatable measurement positions and suitable historical data are important when evaluating corrosion trends and supporting equipment life calculations. Learn more about our UTTM inspection service.C-Scan Corrosion Mapping Inspection
Localised thinning can require more detailed coverage than isolated thickness readings. Ultrasonic corrosion scanning can help identify the distribution of wall loss across the selected area. Our C-Scan Corrosion Mapping service provides mapped thickness information for corrosion assessment, where the technique is suitable for the component and inspection conditions.Ultrasonic Flaw Detection Inspection UTFD
Where cracking is a credible damage mechanism, the examination must address potential crack locations. Appendix 1 includes shear-wave ultrasonic examination in its example strategy. Our Ultrasonic Flaw Detection service can support examinations using a procedure suited to the material, geometry and expected flaw orientation.Radiographic Inspection RT
Profile radiography appears in Appendix 1 as an option for the example localised thinning strategy. Its suitability depends on geometry, examination objectives and radiation safety arrangements. Visit our Radiographic Inspection RT service to discuss the appropriate technique and reporting requirements.Phased Array Ultrasonic Inspection PAUT and TOFD
Phased Array Ultrasonic Inspection PAUT and Time of Flight Diffraction Inspection TOFD may be considered for suitable flaw detection or sizing objectives. These are engineering options to evaluate against the damage mechanism, component geometry and proposed examination procedure. Neither method should be described as automatically mandatory for every PSTT application. Their inclusion and coverage must be justified within the applicable inspection plan and review process.Surface Crack Inspection MPI and DPI
Where a supporting assessment requires accessible surface crack examination, Magnetic Particle Inspection MPI may be suitable for ferromagnetic materials, while Dye Penetrant Inspection DPI may be suitable for surface-breaking discontinuities in non-porous materials. These methods are supplementary options where technically justified. They do not replace thickness assessment, volumetric examination or the other evidence required by the applicable PSTT category.Steam Boiler PSTT: Inspection and Operating Records
Steam boiler eligibility includes automatic control, previous internal periodic inspection, a feedwater treatment system and operation within the specified design boundaries. The guideline also addresses dangerous occurrences, unresolved abnormal conditions, essential fittings and competent boiler personnel. The measured corrosion rate for steam drums, mud drums and headers must be less than 0.125 mm per year. Supporting documents include previous inspection findings, temperature, pressure and water-level monitoring records, feedwater quality records, relevant burner and flame-control maintenance, trip events and operator intervention logs. High-temperature assessment receives specific attention. The guideline calls for microstructural replication analysis in high-temperature zones as a baseline for the first PSTT application, and for subsequent applications where the equipment is susceptible to creep. It also addresses oxide scale thickness where applicable and a creep life fraction rating not exceeding 1.0. Appendix 5 includes damage-related assessment considerations such as high hardness. Where justified, Hardness Testing can provide supporting material condition data. It does not replace microstructural replication or a creep assessment when those are required. The boiler inspection strategy also addresses external thermography, water quality, combustion monitoring, superheater operating pressure and temperature, and external visual inspection. NDT results must therefore be considered alongside the boiler's operating and maintenance history.LPG, Cryogenic Vessels and Special Media
Part C provides a separate route for LPG vessels and specified static vacuum-insulated cryogenic vessels. It references category-specific inspection and testing requirements, including MS 830 for LPG and ISO 21009 or AIGA 116 for the applicable cryogenic vessels. Part D addresses special media. Its application requirements include damage mechanism assessment, risk categorisation and inspection strategy using a recognised RBI methodology, together with an SOE. For vessels containing internal media with prolonged lifespan, previous media replacement observations and future replacement planning are important. The guideline also states that opening such a vessel for complete replacement of the internal media invalidates the CF and requires an application for internal periodic inspection.Safety Critical Elements and PSV Records
Maintenance records for essential fittings form part of the equipment condition evidence. Pressure Safety Valve Calibration can support the maintenance documentation for applicable pressure protection devices. Where suitable for the valve and accepted maintenance scope, PSV Trevi Test Online Calibration may provide supporting set-pressure verification data. Online testing should not be assumed to replace all workshop inspection, servicing or other required valve checks.Preparing a PSTT Application
- Confirm the category and eligibility. Review registration, CF expiry, previous inspection route and exclusions.
- Gather equipment records. Assemble inspection history, thickness data, operating records, maintenance evidence and relevant calculations.
- Assess damage mechanisms and risk. Use the methodology required for the applicable category.
- Prepare the inspection strategy and SOE. Define examination locations, methods and coverage.
- Complete the required submission and review process. Follow the relevant checklist and DOSH discussion requirements.
- Submit traceable findings and prepare for physical inspection. Demonstrate completion of the agreed scope and address review comments.
Frequently Asked Questions About PSTT Inspection
Does PSTT automatically eliminate internal inspection?
No. Eligibility, category conditions, inspection history and the review process determine the applicable route. Parts A and B also prohibit PSTT applications for two consecutive periodic inspections.Is PAUT compulsory for every PSTT application?
No. Methods must address the identified damage mechanisms and required coverage. An advanced method must be technically justified rather than selected solely because it is available.Can current thickness readings prove the corrosion rate?
Current readings establish thickness at the examined locations. A measured corrosion rate requires suitable comparison data and an appropriate calculation. The guideline distinguishes expected and measured corrosion rates for different vessel categories.Does a satisfactory NDT report guarantee PSTT approval?
No. NDT findings are part of the evidence. Eligibility, engineering assessments, operating records, maintenance documentation and the required regulatory review must also be satisfied.Does API 510 inspection replace the statutory inspection process?
No. API 510 Pressure Vessel Inspection can support applicable vessel condition assessments, but it does not replace DOSH or licensed-person functions. Steam boiler assessment must follow the relevant boiler requirements and technical references.Discuss Your Inspection Requirements with CT Precise Engineering
CT Precise Engineering Sdn Bhd provides NDT, integrity inspection, calibration and technical reporting services from Kuantan, Pahang. Our team can discuss the examination scope and supporting technical evidence needed for your equipment assessment. For application preparation and inspection coordination, explore our JKKP DOSH compliance support. Regulatory review, approval and statutory inspection remain with the responsible authorities and authorised parties. Email sales@ctprecise.com with your equipment type, registration details, CF expiry date and available inspection records to discuss the next steps.Source: DOSH Malaysia, 2026 Panduan Permohonan Pemeriksaan Berkala Loji Yang Menghendaki Perakuan Kelayakan Secara Teknologi Termaju bagi Bejana Tekanan dan Dandang Stim, including Parts A–D and Appendices 1–7. Refer to the applicable guideline and category requirements when preparing an application. Official guidance is available through the DOSH Industrial Safety Guidelines portal.
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