Guide for Quality Control Engineers (QC)

  Guide for Quality Control Engineers (QC)

In piping industry, welding is not only a manual skill, but a science and technology based on strict international standards, precise welding locations, and specific procedures to be followed to ensure the quality and safety of the facility.

🔍Understanding welding locations and techniques is essential for every QC engineer responsible for inspecting welds and ensuring that they comply with codes such as ASME Section IX and AWS D1.1.1.

📌 Welding Positions:

🔧 These locations have been designated to ensure welders are tested in various conditions. Each site presents different challenges in terms of gravity and accessibility, and a welder should be qualified depending on the situation in which it will operate.

1. 1G - Flat Position:

🔹 The pipe is placed horizontal

🔹 A welder is only welding from above

✅ The easiest position and is often used in workshops and factories.

2. 2G - Horizontal Position:

🔹 The pipe is in a vertical position

🔹 Welding is done horizontally on the side wall

⚠️ Requires precise control of the welding basin.

3. 5G - Horizontal Fixed):

🔹 The tube is horizontal but cannot be rotated

🔹The welder works on the tube perimeter from bottom to top

💡Includes multiple positions: flat, vertical, and overhead.

4. 6G - Inclined at 45° and steady angle:

🔹 The pipe is fixed at a 45° angle and cannot be rotated

Welding works from all directions🔹

⚠️ The most difficult site, and is used to test the competence of welders because it mimics all situations.

5. 6GR - 6G with Restricted:

🔹 Like 6G but with obstacles that prevent the welding from moving freely.

🔹 Used in very critical work, such as ship structures or complex systems

🧠 Needs a very professional welder.

⚙️ Welding Techniques Used in Pipes (Welding Processes):

Each technique has its properties, and its selection depends on the type of material, tube thickness, and welding location (workshop or site).

1. SMAW (Shielded Metal Arc Welding)

🔸 Widely used in welding carbon steel pipes

🔸 Flexible and works well in outdoor sites

🔸 Suitable for difficult positions such as 5G and 6G.

2. GTAW (TIG – Tungsten Inert Gas):

🔸 Especially used in root passes (Root Pass)

🔸 Ideal for stainless steel (Stainless Steel)

🔸 Gives accurate and clean welders

🔸 It requires high skill.

3. FCAW (Flux Cored Arc Welding) / GMAW (MIG):

🔸 Used in workshops and factories

🔸 Provides high productivity

🔸 Less common in operation pipes due to the need to protect against gases and conditions.

إ Welding Procedures – WPS / PQR according to ASME Section IX:

🔸 WPS (Welding Procedure Specification):

A document that shows the method of welding in detail (matter, position, electrode type, temperature, welding speed... Etc).

🔸 PQR (Procedure Qualification Record):

Demonstration documentation of WPS welding test results, includes mechanical, visual and non-destructive inspections.

🔍 Every technique, welder, material type, WPS and PQR should have it's own.

✅ Important tips for QC quality control engineers:

🔹 Always check the validity of your WPS documents - is it 5G or 6G mode?

🔹Watch the compatibility of Filler Metal with the basic metal

🔹Check the quality of the root pass accurately - it is the basis of good restraint

🔹 Do not forget to check the temperature preheat (Preheat) and post-weld Heat Treatment – PWHT) if found.

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