Wednesday, November 06, 2019

A Last-Minute Glitch

     It's an obscure technical problem, a mechanical issue that comes from having a long length of steel supporting a long length of a non-ferrous metal: something worked out wrong on the spring-loaded suspension system and things that should not be in contact, are.

     I'm confident that it will be worked out.  Or I'll have someone defenestrated, probably a project engineer who has never even been to the site.


RandyGC said...

As Roseanne Roseannadanna's mother said "It's always something".

stuartl said...

You can be sure of one thing - it will NEVER be the project manager's fault.

JayNola said...

Defenestration clears the mind and brings focus like little else. Especially on-site averse engineers.

Anonymous said...

I dont know much about antennae. What bad things will happen if it is left as is? Galvanic corrosion? Does it effect the signal or the load path?

Engineers, they can be your best friend or your worst enemy. We have third party mechanical and structural engineers who are awesome to work with. Our current client however, THEIR engineer insisted we do a specific V-groove weld with backing plates on something that had already passed all the normal tests. It cost us 3 weeks of our construction budget.

I hope you get your issue straightened out as painlessly as possible. it sound like you're in the home stretch

Roberta X said...

Anonymous asks, "What bad things will happen if it is left as is? Galvanic corrosion? Does it effect the signal or the load path?"

Steel and, oh, say copper do not expand and contact the same amount with changes in temperature. Over a long length, call it a thousand feet, this difference can be quite large. At the bottom of the long vertical run, the line turns ninety degrees and ducks under a kind of a girder (a bar joist). At that point, at about 50 degrees, it's in hard contact. In the range from -20 to +100°F, we can expect 8" or more of movement. At one end or the other, there's going to be a lot of force exerted at that point. Something will give. That would be....bad.

Even slight contact can be a problem. We used to have a 6-1/8" line up the outside of the tower. At the very bottom, the back of a 90" flanged elbow rested ever so lightly against an added horizontal support. When we removed it, 25 or more years after installation, there was a long, spindle-shaped flat spot worn on it. At the middle, you could dent the (originally) 1/16"-thick copper with a fingernail. The line is pressurized to about 4 psi to keep out moisture. When it gets wet enough, it can suffer calamitous burnout. It was a ticking time bomb.

JimBob said...

defenestrated-had to look it up!

rickn8or said...

And neither making the transmission line of steel nor the tower out of oh, say copper is a good idea.

This makes the problems I had dealing with hardlines and waveguides in government airplanes look beyond simple.