THE FOUNDATION OF QUALITY AND SAFETY IN GLOBAL INDUSTRIAL PRODUCTION: PROCESS SYSTEMS AND WELDED MANUFACTURING INSPECTION

The operational continuity, efficiency, and—most importantly—occupational safety of industrial facilities are ensured through the integration of complex engineering solutions. All equipment utilized in critical sectors such as chemicals, petrochemicals, energy, oil and gas, food, and pharmaceuticals falls under the umbrella of process systems, which facilitate the safe transport, processing, and storage of fluids and energy.

Welded fabrication is the fundamental joining methodology that ensures the structural integrity of process systems (such as pressure vessels, reactors, heat exchangers, pipelines, and storage tanks). Since welded fabrication is an engineering discipline classified as a "special process"—where errors are difficult to rectify—it is a legal and technical requirement to inspect the work against international standards at every stage of production.

As Experte Teknik Kontrol ve Belgelendirme A.Ş., we provide independent third-party inspection, certification, and surveillance services for process systems and welded fabrication. We do this to help manufacturers competing in the global market validate product quality, eliminate legal risks, and establish sustainable production lines.

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1. WHAT ARE PROCESS SYSTEMS? THEIR ROLE AND IMPORTANCE IN INDUSTRIAL FACILITIES

Process systems are an integrated combination of mechanical, electrical, and automation components involved in the processes of raw material handling, chemical or physical reactions, separation, heating, cooling, and conversion into a final product within an industrial facility.

The main components of a process system are as follows:

• Pressure Equipment and Reactors: Units forming the core of the system, where chemical reactions take place under high temperature and pressure.
• Heat Exchangers: Equipment critical for energy efficiency that facilitates heat transfer between two or more fluids.
• Industrial Piping (Process Piping): Lines designed according to ASME B31.3 or EN 13480 standards that ensure the safe transfer of fluids between units within the facility.
• Storage and Process Tanks: Structures used for storing hazardous, flammable, or chemical fluids at atmospheric or low pressure (API 650, EN 14015).

Even the slightest engineering or manufacturing error during the design, fabrication, and installation of these systems can lead to catastrophic explosions, toxic gas leaks, environmental disasters, and severe economic losses. Therefore, the inspection of process systems is not merely a quality control process but also a risk management activity.

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2. GLOBAL STANDARDS AND REGULATIONS IN WELDED FABRICATION

Welded fabrication is defined as a "Special Process" because its final quality cannot be fully verified (100%) solely through post-production testing; consequently, it requires continuous monitoring throughout the manufacturing process. To gain acceptance in the global market and meet legal requirements, manufacturers must adhere to the following key regulations and standards:

A. Pressure Equipment Directive (PED) 2014/68/EU

Mandatory in the European Union market and in Türkiye, this directive covers the design, manufacturing, and conformity assessment processes for pressure equipment and assemblies with a maximum allowable pressure (PS) exceeding 0.5 bar. Equipment is classified into Categories I, II, III, and IV based on the hazard level of the fluid, volume, or diameter. Experte Teknik Kontrol ve Belgelendirme A.Ş. provides professional technical support under the PED framework, assisting manufacturers with the preparation of technical files, design approvals, and the supervision of hydrostatic testing.

B. ISO 3834: Quality Management System for Welded Fabrication

This is a high-level international standard that defines quality requirements for the fusion welding of metallic materials. It verifies how a manufacturer controls welding quality from both managerial and technical perspectives. Certification is available at three different levels:

• ISO 3834-2 (Comprehensive Quality Requirements): Mandatory for companies manufacturing high-risk process equipment.
• ISO 3834-3 (Standard Quality Requirements): Applicable to medium-risk manufacturing operations.
• ISO 3834-4 (Elementary Quality Requirements): Suitable for low-risk and serial manufacturing.

C. ASME Section VIII (Div. 1 & Div. 2)

This is a pressure vessel design and manufacturing code published by the American Society of Mechanical Engineers (ASME) and recognized worldwide—particularly in the oil, gas, and chemical sectors—as the "gold standard." It mandates strict rules for all processes, ranging from material selection and welding details to post-weld heat treatment (PWHT) requirements and non-destructive testing (NDT) rates.

D. EN 1090: Steel and Aluminum Structural Applications

This is a European standard governing the manufacturing quality of load-bearing steel structures, platforms, and pipe bridges that support process systems. It encompasses Execution Classes ranging from EXC1 to EXC4 and mandates that structural safety be validated through CE marking.

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3. THE BACKBONE OF WELDING QUALITY ASSURANCE: WPS, PQR, AND WQT

For a welded fabrication to successfully pass international inspections, engineering calculations on paper must be verified in the field. This verification is conducted through three fundamental documents, and Experte experts oversee every step of these processes:

1. pWPS and WPS (Welding Procedure Specification)

The WPS (Welding Procedure Specification) serves as the "recipe" for the weld. It is the official document outlining the materials to be used, the welding method (TIG, MIG/MAG, SMAW, SAW), and the specific parameters—such as current, voltage, speed, wire, and gas—that the welder must follow. A preliminary specification (pWPS) is prepared before fabrication begins.

2. PQR (Welding Procedure Qualification Record)

To establish the legal validity of the prepared pWPS, a test coupon is welded in accordance with relevant standards (EN ISO 15614-1 or ASME Sec IX). This coupon, welded under the supervision of an inspector from Experte Teknik Kontrol ve Belgelendirme A.Ş., undergoes both Non-Destructive Testing (NDT) and Destructive Testing (DT—such as tensile, bend, impact, and hardness tests) in a laboratory. Upon the successful completion of these tests, a PQR (Procedure Qualification Record) report is issued, confirming the mechanical suitability of that welding procedure.

3. WQT (Welder Qualification Test)

Once the welding procedure (PQR) is approved, the manual skill of the welders who will apply that procedure in the field must be certified. Welders weld test coupons in accordance with EN ISO 9606-1 or ASME Section IX standards. These coupons undergo fracture, bend, or NDT tests to evaluate the welder's ability to produce defect-free work; upon successful completion, the welder is issued a WQT (Welder Qualification Test) certificate, which is subject to periodic revalidation.

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4. STEP-BY-STEP TECHNICAL INSPECTION AND SURVEILLANCE PROCESS IN PROCESS SYSTEM MANUFACTURING

At Experte Teknik Kontrol ve Belgelendirme A.Ş., the step-by-step inspection activities we conduct—spanning from the initial design phase of a piece of process equipment or a system to its final on-site assembly and commissioning—are as follows:

Step 1: Design and Technical File Review

Before manufacturing begins, engineering drawings, strength calculations, bills of materials (BOM), and weld logs are reviewed. The design's compliance with EN 13445, AD 2000, or ASME codes is verified. NDT plans and ITPs (Inspection and Test Plans) are prepared to establish the "Hold," "Witness," or "Review" points throughout the manufacturing process.

Step 2: Material Acceptance and Traceability Checks

Plates, pipes, flanges, and welding consumables used in process systems must be resistant to high temperatures, pressure, and corrosion. Incoming materials' EN 10204 3.1 or 3.2 material certificates are examined, heat numbers on the materials are checked, and the transfer of these numbers to other parts without erasure during manufacturing is monitored.

Step 3: Pre-Welding and In-Process Checks (Fit-up & Welding Inspection)

Weld bevel preparation, assembly gaps, cleanliness, and the quality of tack welds are inspected (fit-up inspection). During welding, checks are performed to verify whether the welder holds a valid certificate (WQT) and adheres to approved WPS parameters (current, voltage, preheat, and interpass temperatures) by Experte Teknik Kontrol ve Belgelendirme A.Ş.

monitored in real-time by inspectors.

Step 4: Post-Weld Heat Treatment (PWHT) Supervision

Post-Weld Heat Treatment (PWHT) is applied—particularly for thick-walled pressure vessels and pipelines at risk of hydrogen-induced stress—to relieve internal stresses within weld seams. It is verified whether the heat treatment charts (furnace temperature-vs.-time curves) meet standard requirements.

Step 5: Non-Destructive Testing (NDT) and Final Evaluation

Internal and surface defects in welded systems are examined using Visual (VT), Penetrant (PT), Magnetic Particle (MT), Ultrasonic (UT), and Radiographic (RT) testing methods. NDT reports and radiographs are validated by our Level 2/3 experts.

Step 6: Pressure and Hydrostatic Tests (Final Inspection)

A Hydrostatic Pressure Test is performed at a specific multiple of the design pressure (typically 1.25 or 1.43 times) to conduct a final verification of the process systems' leak-tightness and structural integrity. Conducted under the physical witness of an Experte Teknik Kontrol ve Belgelendirme A.Ş. inspector, this test serves as the ultimate proof that the system can be safely commissioned.

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5. BENEFITS OF THIRD-PARTY INSPECTION SERVICES FOR MANUFACTURERS AND INVESTORS

Process system investments involve massive projects with budgets reaching millions of dollars. Working with Experte Teknik Kontrol ve Belgelendirme A.Ş.—an independent, impartial, and accredited inspection and certification body—offers the following advantages for these projects:

• Risk and Cost Management: Detecting errors during manufacturing—while the components are still in the workshop—reduces costs by a factor of 100 compared to discovering them on-site after installation.
• Access to Global Markets: Products manufactured using our approved PQRs, certified welders, and inspected process equipment fully comply with international regulations (CE, ASME, etc.), enabling seamless export to markets worldwide.
• Investor Assurance (Asset Integrity): The shop inspection services we conduct at manufacturers' facilities on behalf of plant investors guarantee that the purchased equipment is produced in 100% compliance with technical specifications and promised quality standards.
• Regulatory Compliance: By fully meeting the requirements of mandatory regulations such as 2014/68/EU, the employer is provided with complete legal protection against potential workplace accidents.

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THE ASSURANCE OF EXPERTE TECHNICAL INSPECTION AND CERTIFICATION INC. IN PROCESS SYSTEMS

Welded fabrication and process systems are structures grounded entirely in mathematical, metallurgical, and engineering principles—areas where there is no room for chance or margin of error. At Experte Technical Inspection and Certification Inc., we document and safeguard every stage of your manufacturing processes, leveraging our extensive industry experience, our commitment to impartiality in line with the EN ISO/IEC 17020 standard, and our team of internationally qualified engineers.

Experte stands by you to ensure your process systems and welded fabrications are safe, sustainable, and meet global standards. Contact us for your technical inspection, surveillance, WPS/PQR preparation, and certification needs, and let us showcase your quality to the world together.