How to Install a Weldolet

The installation of a Weldolet must strictly adhere to standards and specifications to ensure the strength, sealing, and safety of the connection.

Weldolets Installation Steps

The installation of a Weldolet involves preparing materials, cutting a hole in the main pipe, aligning and temporarily fixing the Weldolet, welding it securely, performing post-weld cleaning and testing, and conducting a pressure test to ensure no leaks.

Check Materials: Ensure that the materials, dimensions, and specifications of the Weldolet, main pipe, and branch pipe meet the design requirements.
Clean Surfaces: Remove oil, rust, and other impurities from the connection areas of the main pipe and Weldolet.
Mark Position: Mark the location for the branch pipe connection on the main pipe to ensure accuracy.

Select Cutting Tools: Use appropriate cutting tools (e.g., drilling machine or plasma cutter) to create a hole in the main pipe.
Hole Size: The hole diameter should match the inner diameter of the Weldolet’s branch end, ensuring smooth and burr-free edges.

Position the Weldolet: Align the Weldolet with the hole on the main pipe, ensuring it is aligned with the axes of the main pipe and branch pipe.
Temporary Fixing: Use clamps or tack welding to temporarily secure the Weldolet to the main pipe.

Select Welding Method: Choose the appropriate welding method (e.g., TIG, MIG, or manual arc welding) based on the material and working conditions.
Welding Process: Strictly follow welding procedure specifications to ensure weld quality.

Perform root welding first to ensure sealing.
Then proceed with fill welding and cap welding to ensure weld strength.

Welding Sequence: Use symmetrical welding to avoid deformation.

Clean the Weld: Remove slag and spatter, and inspect the surface quality of the weld.
Non-Destructive Testing: Perform non-destructive testing (e.g., radiographic or ultrasonic testing) on the weld as needed to ensure it is defect-free.
Anti-Corrosion Treatment: Apply anti-corrosion treatment (e.g., painting or coating) to the welded area to extend its service life.

6. Pressure Testing

Hydrostatic or Pneumatic Testing: Conduct a pressure test on the piping system to ensure there are no leaks at the Weldolet connection.

Installing Weldolets

Pipe Preparation: Both the main pipe and the branch pipe are carefully prepared, with the main pipe typically requiring a beveled end for easy welding.
Welding: The weldolet is professionally welded onto the main pipe using suitable welding methods such as MIG, TIG, or stick welding.
Threaded or Socket Weld: The branch pipe is securely connected to the weldolet using either threaded or socket weld, depending on the type of branch pipe.
Inspection: Rigorous inspection is carried out to ensure the highest welding quality with no leaks or defects.

Precautions

Safety First: Wear protective gear (e.g., welding mask, gloves) during welding to ensure safety.
Welding Quality: Welding must be performed by certified welders to ensure the weld meets standards.
Size Matching: Ensure the dimensions of the Weldolet, main pipe, and branch pipe match to avoid installation errors.
Environmental Conditions: Avoid welding in humid or extreme temperature conditions to prevent compromising weld quality.
Comply with Standards: The installation process must comply with relevant standards (e.g., ASME B31.3, API 1104).

Tools and Equipment

Cutting tools (drilling machine, plasma cutter, etc.)
Welding equipment (welding machine, electrodes, shielding gas, etc.)
Clamps or tack welding equipment
Cleaning tools (wire brush, grinder, etc.)
Testing equipment (non-destructive testing equipment, pressure testing equipment, etc.)

Branch Connections and Welding Requirements in ASME B31.3-2018

Preparation for Branch Connections

Run openings for branch connections shall not deviate from the required contour more than the dimension m in Figure 328.4.4. In no case shall deviations of the shape of the opening cause the root spacing tolerance limits in the WPS to be exceeded. Weld metal may be added and refinished if necessary for compliance.

The root opening of the joint shall be within the tolerance limits in the WPS.

Branch Connections and Welding Requirements

(a) General Details

Figures 328.5.4A through 328.5.4F illustrate acceptable details for branch connections, both with and without added reinforcement, where the branch pipe is directly connected to the run pipe. These illustrations are typical and do not exclude other acceptable construction types not shown.

(b) Weld Attachments

Figure 328.5.4D depicts basic weld attachment types used in branch connection fabrication. The location and minimum size of attachment welds must comply with specified requirements. Welds must be calculated per para. 304.3.3 but should not be smaller than the sizes shown in Figure 328.5.4D.

Figure 328.5.4F shows attachment weld types for integrally reinforced branch connection fittings. The location and minimum weld size must conform to the requirements outlined in section (i) below.

(c) Nomenclature and Symbols

Tb: Nominal thickness of the branch.

Th: Nominal thickness of the header.

Tm: Nominal thickness of the branch weld for integrally reinforced fittings, determined by:

(1) Manufacturer specifications,

(2) Full depth of the weld groove after fit-up (if no manufacturer specification),

(3) Engineering design documentation per para. 300(c)(3), or

(4) Calculations per para. 304.7.2.

Tr: Nominal thickness of the reinforcing pad or saddle.

tc: Lesser of 0.7Tb or 6 mm (1/4 in.).

tmin: Lesser of Tb or Tr.

(d) Branch Connection Welds

Branch connections, including fittings (per paras. 300.2 and 304.3.2), must be attached to the run pipe using fully penetrated groove welds. Cover fillet welds with a throat dimension not less than tc are required. See Figure 328.5.4D, illustrations (1) and (2).

(e) Reinforcing Pad or Saddle Attachment

A reinforcing pad or saddle must be attached to the branch pipe by:

(1) A fully penetrated groove weld with a cover fillet weld (throat dimension ≥ tc), or

(2) A fillet weld with a throat dimension ≥ 0.7tmin. See Figure 328.5.4D, illustration (5).

(f) Reinforcing Pad or Saddle to Run Pipe

The outer edge of a reinforcing pad or saddle must be attached to the run pipe by a fillet weld with a throat dimension ≥ 0.5Tr. See Figure 328.5.4D, illustrations (3), (4), and (5).

(g) Reinforcing Pad or Saddle Requirements

Reinforcing pads and saddles must fit well with the attached parts. A vent hole must be provided on the side (not at the crotch) to detect leaks and allow venting during welding and heat treatment. Pads or saddles may consist of multiple pieces if joints have strength equivalent to the parent metal and each piece has a vent hole.

(h) Examination and Repairs

The completed weld between the branch and run must be examined and repaired (if necessary) before adding a reinforcing pad or saddle.

(i) Integrally Reinforced Branch Connections

Figure 328.5.4F shows integrally reinforced branch connections typical of MSS SP-97 fittings. These are attached to the run pipe by full penetration groove welds, finished with cover fillets (throat dimension ≥ tc). The cover fillet weld must smoothly transition to the attachment weld and run pipe or fitting.

Fabricated Laps

Figure 328.5.5 shows typical fabricated laps, which must be fabricated in accordance with the requirements of para. 328.5.4.

Welding for Severe Cyclic Conditions

Welding procedures must ensure a smooth, regular, and fully penetrated inner surface for applications involving severe cyclic conditions.

Summary

The requirements for branch connections and welding include detailed specifications for weld types, sizes, and attachment methods. Reinforcing pads or saddles must fit well, have vent holes, and be attached with appropriate welds. Inspection and repairs must be completed before adding reinforcements. Fabricated laps and welding for severe cyclic conditions must adhere to specified standards to ensure structural integrity and performance.

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Weldolets – a detailed guide

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