Welding QC Inspector Interview Questions

This article is about Welding QC Inspector Interview Questions of Aramco Welding CBT test. Questions are based international codes and standards.

1. How is the Procedure Qualification Record (PQR) different from the WPS (Welding Procedure Specification)?

Answer: The Procedure Qualification Record (PQR) differs from the Welding Procedure Specification (WPS) in that it serves to certify that test welds conducted in accordance with the WPS comply with the requirements outlined in the relevant Code. The PQR provides a summary of the specific test results, ensuring that the welding procedure has been qualified and meets the necessary standards.

2. What is a “Weld Map” and how is it used?

Answer: A “Weld Map” is an isometric drawing that displays the location and numerical identification of each weld used in the construction of a process piping system. It provides a visual representation of the welding joints in the system. Each completed weld is labeled with its corresponding weld number as indicated on the weld map, along with the date of completion and the identification number or code of the welder or welding operator involved. The weld map serves as a reference tool for tracking and managing the welding activities during the construction process, ensuring proper documentation and traceability of each weld.

Question-3 What are the welder qualification limits?

Answer: The welder qualification limits include several factors that determine the scope and validity of a welder’s qualification. These limits are as follows:

Base metal qualification limits: The qualification of a welder is specific to the base metal being welded, which is determined by the P number (base metal grouping) and thickness range. Welders are qualified to work within these specified limits.
Filler material qualification limits: Welders must be qualified for specific filler materials, identified by the F number (filler metal grouping). The qualification ensures that the welder is capable of working with the approved filler materials.
Pipe diameter and position qualification limits: Welders are qualified for specific pipe diameters and positions. This means they are certified to perform welding work within the specified range of pipe diameters and in certain positions, such as horizontal, vertical, or overhead.
Weld metal thickness qualification limits: Welders are qualified to work with specific weld metal thicknesses. This qualification ensures that the welder is capable of producing sound and acceptable welds within the specified range of weld metal thicknesses.

Question-4: What is the chemical composition of a low hydrogen electrode – E7018?

Answer: The chemical composition of a low hydrogen electrode, specifically E7018, is as follows:

Carbon (C): 0.15%
Manganese (Mn): 1.60%
Silicon (Si): 0.75%
Phosphorus (P): 0.035%
Sulfur (S): 0.035%
Nickel (Ni): 0.30%
Chromium (Cr): 0.20%
Molybdenum (Mo): 0.3%
Vanadium (V): 0.08%

These chemical composition values indicate the percentage of each element present in the electrode. E7018 is known as a low hydrogen electrode due to its low hydrogen content, which helps reduce the potential for hydrogen-induced cracking in the weld metal.

Question-5: How can you verify that the received electrode has the chemical composition as per Material Test Certificate (MTC)?

Answer: The verification of the chemical composition of received electrodes can be done through the following methods:

Chemical Analysis Method: The electrode samples can be sent to a laboratory for chemical analysis. The laboratory will perform tests to determine the exact chemical composition of the electrode and compare it against the specified composition mentioned in the Material Test Certificate (MTC).
Verification of Heat Number and Lot Number: The electrode packaging should have the heat number and lot number mentioned on it. These numbers can be cross-checked with the information provided in the MTC. If they match, it provides assurance that the received electrodes belong to the same batch with the specified chemical composition.

Question 6: What are the tests required for the analysis of consumables and the standard for this analysis?

Answer: The following tests are commonly performed for the analysis of welding consumables, including electrodes:

Chemical Analysis Method: This test determines the chemical composition of the consumables, including the percentages of various elements. It helps verify if the consumables meet the specified composition requirements.
Positive Material Identification (PMI): PMI is a non-destructive testing method that uses specialized equipment to analyze the elemental composition of materials. It can be used to verify the chemical composition of consumables without damaging them.

The standard for these analyses is usually referenced from ASME Section II Part C (Materials). ASME Section II provides guidelines and requirements for materials used in various industries, including welding consumables.

Question 7: How do you calculate the weld repair percentage?

Answer: The weld repair percentage can be calculated using the following formula:

% RR = (Lr / Lw) x 100

Where: % RR – Percent repair rate Lr – Total length of repair in one week Lw – Total length of weld radiographed in one week

To calculate the weld repair percentage, divide the total length of repairs performed in a week (Lr) by the total length of welds radiographed in the same week (Lw). Multiply the result by 100 to express it as a percentage.

This calculation provides an indication of the extent of repairs required in relation to the total weld length radiographed, giving insight into the quality and efficiency of the welding process.

Question 8: What is the SAES standard for the storage and handling procedure of low hydrogen electrodes?

Answer: The SAES standard for the storage and handling procedure of low hydrogen electrodes is SAES-W-011, specifically Appendix A. This standard provides guidelines and requirements for the proper storage, handling, and control of low hydrogen electrodes to ensure their quality and prevent moisture absorption, which can lead to hydrogen-induced cracking during welding. Adhering to this standard helps maintain the integrity of low hydrogen electrodes and ensures their optimal performance during welding operations.

Question 9: What does “L” stand for in 316L, and what is the composition of 316L?

Answer: The “L” in 316L stands for “Low Carbon.” 316L is a low carbon variation of the austenitic stainless steel grade 316. The composition of 316L typically includes:

Chromium (Cr): 16-18%
Nickel (Ni): 10-14%
Molybdenum (Mo): 2-3%
Iron (Fe): Balance
Other elements such as manganese, silicon, phosphorus, sulfur, and carbon in reduced amounts compared to standard 316 stainless steel.

The low carbon content in 316L offers improved corrosion resistance, particularly in environments where welding is involved. It helps to prevent sensitization and carbide precipitation, which can lead to intergranular corrosion. Therefore, 316L is commonly used in applications that require excellent corrosion resistance and weldability.

10) What are the criteria for selecting welding consumables?

Answer: Welding consumables should be selected based on several criteria, including:

Mechanical properties: The consumables should possess suitable mechanical properties that meet the requirements of the intended application.
Compatibility: They should be compatible with the base materials to be joined, ensuring proper bonding and minimizing the risk of metallurgical issues.
Service suitability: The consumables should be suitable for the intended service conditions, such as corrosion resistance, high or low temperature environments, or specific industry requirements.
Welding conditions: Considerations such as polarity, welding position, and direction play a role in selecting consumables that provide optimal performance and ease of use.

11) What is meant by low hydrogen consumables?

Answer: Low hydrogen consumables, also known as low hydrogen electrodes or rods, are welding consumables with a low hydrogen content. The term “low hydrogen” refers to the amount of diffusible hydrogen present in the deposited weld metal. Generally, low hydrogen consumables contain hydrogen levels less than or equal to 8 milliliters (ml) of hydrogen per 100 grams (g) of deposited weld metal. This low hydrogen content helps to minimize the risk of hydrogen-induced cracking, particularly in high-strength steels and critical applications.

12) What are dissimilar metal welds?

Answer: Dissimilar metal welds refer to weld joints between two different types of metals or alloys. These joints involve joining materials with distinct chemical compositions and metallurgical properties. Common examples of dissimilar metal welds include:

Ferritic steel and austenitic stainless steel
Ferritic steel and duplex stainless steel
Ferritic steel and nickel-based alloys
Use of stainless steel or nickel-based filler metals on ferritic steels

Dissimilar metal welds require careful consideration of material compatibility, joint design, and appropriate welding techniques to ensure proper bonding and minimize the risk of metallurgical issues, such as galvanic corrosion or mechanical failures.

13) Can you provide the names of two aluminium flake weldable primers? What is the maximum coating thickness allowed?

Answer: Two examples of aluminium flake weldable primers are Bloxide and Deoxaluminate. These primers are designed for use on aluminum surfaces to improve adhesion and provide a protective coating before welding.

The maximum coating thickness allowed for these primers should not exceed 0.050mm (0.002 inches). It is important to follow the manufacturer’s instructions and recommended application thickness to ensure optimal performance and compatibility with the welding process.

14) What is the heating and cooling rate for Post Weld Heat Treatment (PWHT)?

Answer: The heating and cooling rates during PWHT are specified to ensure proper heat treatment of the welded component. According to industry standards, the heating and cooling rates above 316°C (600°F) should not exceed 222°C/hr (400°F/hr) divided by the weld thickness in inches. However, in no case should the heating and cooling rate be higher than 222°C/hr (400°F/hr). These rates help to control the thermal gradients and reduce the risk of thermal stresses and distortion in the material.

15) Under what conditions are remote current controls used in field welding?

Answer: Remote current controls are used in field welding under the following conditions:

Distance from welding power source: If the welding location is more than 30 meters (approximately 100 feet) away from the welding power source, remote current controls are employed. This ensures that the welders can adjust and control the welding current conveniently from their working position.
Welding in remote locations: When welders are working in remote or inaccessible locations, such as elevated pipe racks or confined spaces, remote current controls are necessary. These controls allow the welders to adjust the welding current without the need to be physically present near the welding power source.

The use of remote current controls enhances the flexibility and convenience of welding operations in field environments, providing better control over the welding process and maintaining optimal welding conditions.

Welding QC Inspector Interview Questions – Aramco Welding CBT