How do I avoid the over-bitten pittsburgh seam (crushing the pocket)?
1st YearGREEN · Field Reference#418Answer
You are hand-seaming a custom offset transition fitting. You use your tongs to lock down the starting lip of the Pittsburgh pocket, but you squeeze the handles so violently that you crush the receiving pocket channel completely closed, making it impossible to slide the matching flange sheet home.
Hand seamers are for setting spatial angles, not for crushing mechanical pockets. Adjust the internal set-screw stop on the handles of your seamers to physically block the jaws from closing past the single-ply metal thickness, allowing you to set the. The likely recovery is to check the tool setup, correct the prep or technique if it is within your assignment, and bring the journeyman or foreman clean information before the work creates rework overhead.
What to check first
- Check the raw edge, pocket, or overlap before locking the joint.
- Seat the tool fully and square before applying force.
- Use a full controlled stroke when the tool needs a mechanical lock.
- Test the fit before sending the piece overhead.
- Remake or re-edge the part if the lock will not hold.
Ask Foreman
You crushed the Pittsburgh pocket shut with the tongs. Back the jaws off, pry the pocket open with a flat screwdriver, and set the tool's handle stop screw so you can't flatten the channel track.
Do not do this
Do not force the tool through the problem or substitute the wrong tool just to keep moving.
Why it matters
Bad tool execution damages material, slows the journeyman down, and can create leaks, failed joints, damaged equipment, or safety hazards.