Full Analysis Of Welding Procedure Qualification: Process, Standards And Practical Guide

Full analysis of welding procedure qualification: process, standards and practical guide

If the welding evaluation fails to meet the requirements, then in minor cases there will be rework and loss of money, and in serious cases it will lead to safety accidents. However, it is this link hidden behind the drawings that is actually the key to protecting the quality of the project performance.

What exactly is a welding review?

Many people have heard of welding process qualification, but they may not necessarily know it for sure. It is actually a set of rigorous verification processes. Its purpose is to prove that the welding method, materials and parameters you choose can weld qualified joints and rank first in Jiangsu in 2025. A factory that manufactures pressure vessels skipped the welding process qualification and went directly to production. As a result, the weld flaw detection pass rate of 20 storage tanks did not reach 60% . How to conduct quality inspection of hybrid joints of welding and riveting , resulting in losses of more than 3 million yuan.

A complete set of welding qualifications covers two core documents, the welding procedure specification, also known as WPS, which describes the specific welding method, and the process qualification report, or PQR, which can confirm that such welding is indeed feasible. These two documents are indispensable like recipes and tasting reports.

Why it has to be done

The Technical Safety Specification for Special Equipment TSG 21-2025 clearly stipulates that boilers must undergo welding process qualification, pressure vessels must also undergo welding process qualification, and pressure pipelines must also undergo welding process qualification. This is an untouchable legal red line. In February 2026, the Zhejiang safety supervision department launched a surprise inspection, and 12 companies were ordered to suspend production for rectification due to lack of welding process assessment.

From a quality perspective, welding evaluation can detect fatal defects such as cracks, lack of fusion, and pores in advance. A certain shipyard in Shanghai received a batch of export orders last year. During the welding evaluation, it was discovered that the preheating temperature of the high-strength steel was insufficient . How to perform quality inspection on the hybrid joints of welding and riveting , adjustments can be made in a timely manner, thus avoiding the rework of the entire ship's welds and saving nearly one million in costs.

How to choose standards

The commonly used domestic standard is NB/T 47014-2025 "Welding Procedure Qualification for Pressure Equipment", and ASME IX or ISO 15614 is commonly used in international projects. In January this year, some chemical equipment from Shandong was exported to Europe. The welding evaluation was not recognized simply because the wrong standard was selected, and the re-evaluation delayed the construction period by 45 days.

Various standards have huge differences in their requirements for impact energy. NB/T 47014 stipulates that the average value of three specimens must not be less than 41J, while ASME IX may require 34J. When selecting standards, be sure to carefully read the requirements set forth in the contract and design documents, and do not rely solely on subjective assumptions.

How to go through the complete process

The first step is to confirm the assessment conditions. In December 2025, for a bridge project in Guangdong, the base material is high-strength steel such as Q690D, with a thickness of 80mm. Before the assessment, it is necessary to clarify the method used for welding, whether it is gas-shielded welding or submerged arc welding, and whether the joint form is butt or corner joint.

The second step is to prepare the assessment plan. Sufficient margin must be reserved for the size of the test plate. Usually the length of the butt test plate shall not be less than 600 mm. The welding parameters must be recorded in detail. Current, voltage, welding speed, and interlayer temperature are all indispensable.

The third step is to weld the test plate. This link must be operated by a certified welder. When the temperature of the on-site environment is lower than 0°C, corresponding preheating measures must be carried out. During the welding evaluation at a construction site in Beijing in January 2026, because the temperature at that time was minus 8°C, cracks appeared on the test plate. The root cause was found to be that the preheating requirements were not followed.

The fourth step is to conduct a comprehensive inspection. First, carry out a visual inspection to check the forming status of the weld, then conduct a radiographic inspection to observe whether there are internal defects, then cut the sample, and then perform stretching, bending and impact testing. The data collected by the inspection directly determines whether the welding evaluation is passed.

What are the common pitfalls?

The coverage of welding assessment has been misunderstood by many people. The process qualified for carbon steel Q235B assessment cannot be directly used for Q345R. In August 2025, a manufacturing plant in Hebei used carbon steel welding assessment to weld low alloy steel. As a result, the impact energy of batch welds failed, and rework caused a loss of 1.5 million.

Moreover, there is a situation of welding material management. The drying, insulation and use of welding rods must be fully recorded. At the end of last year, there was a pressure vessel factory in Hunan. During the welding evaluation, the welding rods were affected by moisture and were not dried. The result of the tensile test was that all test pieces broke at the welds. Full analysis of welding process evaluation: process, standards and practical guidelines, and a full two weeks of time was wasted for no reason.

How to choose an institution

The threshold is hard on qualifications. What is more reliable is that the institution can issue CNAS and CMA reports at the same time, and its coverage includes NB, ASME, and ISO standards. The 2025 industry white paper shows that the number of domestic institutions with full testing capabilities is less than 40.

The equipment used for testing is also quite crucial. A 300kN universal testing machine must be equipped to carry out tensile testing, and an imported spectrometer must be used to review the composition of the base material. A testing agency in Nanjing added a fully automatic impact testing machine this year. Its efficiency has been improved by as much as three times, and a report can be issued in only 3 days.

How do you conduct quality inspection on hybrid joints of welding and riveting in the welding evaluation projects you carry out? What are the inspection items that you have encountered that are most difficult to successfully pass? Describe your personal experience in the comment area, like and save this article, and follow it directly the next time you do a welding review.