Drilling Steel Purlins

mdshunk

How large of a hole may be field drilled in the bottom flange of a z shaped steel purlin in metal pre-fabricated buildings? (Kirby building).

Standstrong

No self tappers?
Thats what we have been using.
Hans

joasis

1/3 the width of the flange, since the manufacturer of the purlin is an un known. US Steel purlins ( US made) state 1/2 the flange, with one allowed every bay. Prefered hole placement is the web, hole varies depending on distance from the frame.

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mdshunk

Thank you for that.

I posted this a good while back, and nobody responded, so I took another route.

I was putting some high bay lights in a small warehouse that was just constructed. I thought I had a bright idea. The high bay lights have a hook that they hang from. I thought maybe I could drill a hole in the bottom flange of the Z purlin, and hang the fixture right on there. As I couldn't find out if this was permitted, I went the normal route and used a beam clamp on the flange with an eye bolt screwed into the beam clamp. I guess I should quit trying to reinvent the wheel. I didn't want to be the guy responsible for trashing a hundred purlins to save 4 bucks a fixture by not having to use a beam clamp and an eye bolt.

joasis

Why didn't you just say what you were doing, anyway? Our electrician never asks me, he just does it...says I better hope it holds up his light!

He uses 3/8 inch eye bolts for high bay lights...never a problem.

When I worked for a steel building manufacturer, we allowed extra steel for all kinds of point loads, like suspended heaters, basketball goals, scoreboards, etc...but never lights. Now while we added the steel, either extra pulins for a load, or an I beam, the engineeres always removed them whent he building went to actual print. We added it primarily so the engineer could add if needed.

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