Pipe Welding Time Calculation: Fast Estimation of Man-Hours
It must be understood that a quick calculation with a good approximation of welding man-hours is crucial to making correct decisions in project management.
This guide divides pipe welding into two main categories to help estimate the time required:
Categories of Pipe Welding for Man-Hour Estimation
- Piping with Quality Control by Hydrostatic Testing Only
- Piping with Quality Control by Hydrostatic and Non-Destructive Testing (e.g., Radiographic Testing [RT], Ultrasonic Testing [UT])
Estimating Pipe Welding Man-Hours
In modern piping projects, contractors use detailed engineering methods, such as isometric drawings and pipe models, to facilitate efficient construction in the workshop and easy assembly on-site.
Piping Works and Spool Fabrication
Each isometric line is divided into sections called spools, which are fabricated in the shop. After manufacturing, these spools are transported to the construction site for adjustment, positioning, and final welds.
Typically, with well-planned engineering, 70-90% of the welds are performed during prefabrication, significantly reducing costs and man-hours.
This also helps meet construction deadlines by minimizing the impact of adverse weather conditions on-site.
Benefits of Shop vs. Field Welding
It is well-established that welds made in the shop are faster and offer better quality control than those performed in the field.
Welding times vary depending on several factors:
- Material Type: This guide focuses on carbon steel pipes.
- Pipe Thickness: Thicker pipes require more time for bevel preparation and welding because more material needs to be filled.
- Pipe Diameter: Larger diameter pipes are more challenging to handle and weld.
Standard Welding Times for Carbon Steel Pipes
Type 1: Welding with Hydrostatic Testing Quality Control Only
- For a standard 4-inch carbon steel pipe:
- Field Welding: 0.70 man-hours per inch of welding
- Prefabricated Welding: 0.40 man-hours per inch of welding
- With a crew (helper, journeyman, and welder) working 10 hours per day:
- Approximately 42 inches per day can be welded in the field.
- Approximately 75 inches per day can be welded in the shop.
Note: These times apply under standard working conditions without economic incentives for higher performance. For more detailed insights, see "Estimator's Piping Man-hours Tool."
Type 2: Welding with Hydrostatic and Non-Destructive Testing Quality Control
- For the same 4-inch carbon steel pipe:
- Field Welding: 2.0 man-hours per inch of welding
- Prefabricated Welding: 1.0 man-hours per inch of welding
- With a crew working 10 hours per day:
- Approximately 15 inches per day can be welded in the field.
- Approximately 30 inches per day can be welded in the shop.
Note: These times also apply under standard working conditions. For further information, please refer to "Estimator's Piping Man-hours Tool."
Important Considerations for Pipe Welding Man-Hour Calculations
The welding time calculations include only the following:
- Piping welding
They do not account for:
- Complicated pipe handling
- Painting
- Insulation
- Supports and clamps
- Scaffolding for piping
Conclusion: Optimizing Welding Man-Hours
A quick estimation of welding man-hours is essential for making informed decisions in project management.
By utilizing historical performance data and taking into account factors like material, thickness, pipe diameter, and carbon steel pipe grade, project managers can swiftly quantify the piping job. Although this quantification is an estimate, it serves as an invaluable tool for effective project management
