What are the process steps for welding steel pipes

First, what is the process flow for welding steel pipes? 
Installation preparation - grooving - hole drilling - machinery installation - tees/crosses - steel pipe installation - system pressure testing.

Second, what are the preparation steps for welding steel pipe installation?
1. Inspect the hole drilling machine, grooving machine, and pipe cutting machine to ensure safe use.
2. Prepare materials and tools, including pipes, steel tape measure, wrenches, vernier calipers, level, lubricant, wooden mallet, scaffolding, etc.
3. Install the supports and hangers for the steel pipes according to design requirements.

Third, what are the details of grooving in the welding steel pipe process?
1. Cut the steel pipe to the required length using a pipe cutting machine. Use a level to check the cut surface to ensure it is perpendicular to the central axis of the steel pipe. If there are burrs on the cut, grind them smooth with a grinding wheel.
2. Place the steel pipe to be grooved on the grooving machine and its tailstock, and level it with a spirit level to ensure the pipe is horizontal.
3. Place the end of the steel pipe to be grooved against the grooving machine, ensuring the pipe's centerline is perpendicular to the roller surface.
4. Slowly press down the jack to press the upper pressure roller firmly against the steel pipe. Start the grooving machine, rotating the roller one full turn. Observe whether the steel pipe section is still firmly against the grooving machine. If not, adjust the pipe to be horizontal. If it is firmly against the machine, slowly press down the jack to evenly roll the steel pipe to the predetermined groove depth.
5. Stop the machine and use calipers to check the groove depth and width. After confirming that it meets the standard requirements, unload the jack and remove the steel pipe.

Fourth, what are the details of opening holes in the steel pipe welding process? Installing mechanical tees and crosses:
1. Mark the steel pipe with an ink line to determine the location of the branch pipe opening.
2. Secure the chain-driven hole drill to the designated hole location on the steel pipe.
3. Start the motor and turn the handwheel to slowly bring the drill bit closer to the steel pipe. Simultaneously, apply lubricant to the drill bit to protect it. Complete the hole drilling process.
4. Stop the machine, turn the handwheel to disengage the chain, remove the hole drill, clean away any metal fragments and debris from the drilled area, and smooth the hole with a grinder.
5. Place the clamp onto the steel pipe, ensuring the mechanical tee is concentric with the hole, the rubber sealing ring is evenly spaced from the hole, and the bolts are tightened securely.
6. If using a mechanical four-way connector, ensure the holes on both sides of the steel pipe are concentric during drilling. Otherwise, the rubber ring may break after installation, affecting the water flow area.

Fifth, what precautions should be taken when installing welded steel pipes?
Following the principle of installing large-diameter main pipes and risers first, followed by small-diameter branch pipes, the installation process must be carried out sequentially and continuously. Skipping or segmented installation is not allowed to avoid difficulties in connecting sections and affecting the overall performance of the pipeline.
1. Fix the steel pipe to the support bracket and place a non-damaged rubber sealing ring on the end of one steel pipe.
2. Insert the other steel pipe, with lubricant applied to its circumference, into the rubber sealing ring and rotate it until it is in the center of the joint.
3. Install the upper and lower clamps on the outside of the rubber sealing ring, and push the convex edge of the clamp into the groove. Firmly press the ears of the upper and lower clamps. Install bolts at the bolt holes of the clamps and tighten the nuts evenly and alternately. While tightening the nuts, use a wooden mallet to tap the clamps to ensure that the rubber sealing ring does not wrinkle. The convex edge of the clamp must be fully inserted into the groove.
4. Add supports to the steel pipe within 500mm of the rigid clamp joint.

Sixth, what precautions should be taken when performing system pressure testing on welded steel pipes? 
After installation, a system pressure test should be conducted. Before the system pressure test, a comprehensive inspection should be performed to ensure that all installation components and fixed supports are in place. Installed steel pipes may sag; if the sag is significant, additional supports can be added; if the sag is minor, it will naturally disappear as the pressure inside the pipe increases.