flanging 5

Brighton Corporation abides by the standards of the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code.  This document sets the specifications for the metal fabrication we engage in.  As this applies to flanging, we often go beyond what the code calls for.  Such as circumference.  I don’t even know what the code requires, but our standard is plus or minus an eighth of an inch.  No matter how large or small of a tank end.  Our straight flange (the straight edge of the tank end that extends above the curved corner) is plus or minus a quarter inch in length and two and a half degree of toe in or toe out from perfectly straight.  The inside corner radius we form can be slightly larger than called for, but not smaller.  The overall height can be one and a quarter per cent of the diameter of the head deep to five-eighths of a per cent of the diameter of the head shallow than what is called for.  Thin out allowed is fifteen per cent of the original thickness.  Out of round can be one per cent of the diameter.  Bevels (the edge cut to a certain angle, inside or outside) can be plus or minus two and a half degrees of what is called for.  Tapers (the edge cut to a certain thickness at a certain angle, inside or out, which can be longer than called for, but not shorter) can be plus one sixteenth of an inch and minus nothing.  Bore-ups (the edge cut perfectly straight to a certain thickness and a certain length, blended in with a taper at the bottom) need to be pretty much dead on, and like tapers can be longer but not shorter.  The radius, which is the depth the flat plate is pressed to by the press operators (which we have to maintain, even if it is a crappy press job to begin with) can be plus or minus a quarter inch of the template used to form it with.  These are most of the specs we must meet, although I’m sure I’ve missed some.

Except customers can request (and pay dearly for, I hope) specs more restrictive than code.  Such as ridiculously small thin out.  Or overall heights.  Or out of rounds.  Or perfectly straight flanges.  Or circumferences even closer than an eighth inch.  Or tapers to a thirty-second of an inch, or less.  Even weights have to be held to certain limits for some customers, which is illogical since the mills producing the plate cannot guarantee the metal won’t be a little heavy or light.  Some customers require a perfect radius.  Some customers request tighter tolerances on any combination of these things, or on everything.  Which gets ludicrous.  We are a metal fabrication shop, not a machine shop.  Machine shops can do extremely fine work on small pieces.  The tank ends we work on range from five inches to over three-hundred inches in diameter.  Huge pieces of metal to try to form to such exacting specs.

Normally, we are the last machine the tank ends pass through (unless they get polished, in which case they go to the polisher).  After us comes inspection.  Lately, we flanger operators have inspected our own work ourselves.  Things go much more smoothly this way.  But most of the time I’ve been at Brighton we’ve had an inspection department.  We’ve always had a quality control department, with or without inspectors.  Ray M. was the QC manager when I was hired.  He had the final say on whether a piece got sent back for rework or not.  No one overruled him.  No QC managers we’ve had since he retired have had such authority.  The inspector we had when I first started was another old guy, Don M.  When he found something he didn’t like he would call you over and show it to you.  You were expected to fix your own mistakes (unless you messed something up so badly you didn’t know how to fix it).

There are a lot of things that can go wrong.  The worst is if you squeeze a tank end below the minimum thickness.  There is no way to make a head thicker.  If a head is thinned out then it is scrap.  Most everything else can be fixed.  Just not necessarily by you.  If metal shavings get crushed into the piece by the icr roll while you are machining the edge, the shallow pits can be belted out on a polisher while the deep pits need to be welded up.  Or if you hump up the radius while forming the head, it would have to go back to the press to be smoothed out.  There are so many things that can go wrong.

When I first went to work on my own I was supposed to go to my foreman with any problems.  Only Jim D. knew nothing about flanging.  When a head I had done turned up being three-sixteenths inch deeper than acceptable, he signed for it, saying, “Who can see three-sixteenths of an inch?”  That was the last time he ever said that.  He got chewed out for that, once Ray saw the inspection sheet.  All inspection reports cross the QC manager’s desk.  Inspection was a humorless job.

But I still had some fun with them.  Bill R. was an inspector who’d lost most of a finger while operating a metal shear.  When he’d take his gloves off and lay them down, I’d sneak up and slip a piece of chalk into the finger of the glove that his bit of a finger went into.  Then I’d watch to see how long it took for the chalk to work its way down and reach his stub.  When he finally felt it he’d yank the glove off and pull the chalk out and glare all around to see who was messing with him.  Sometimes it would take an hour before he realized the chalk was in there.  Most of the inspectors were totally without humor.  I’m glad they’re gone.

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