Del Underwood: About the Author
Det Norske Veritas
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Published Articles
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May/June 2011 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
In two previous issues we discussed the important difference between steady and cyclic loading, and why loose bolts fail while tight ones do not. This issue will offer two suggestions for reducing the tendency for bolts to become loose.
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March/April 2011 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
In the previous issue we dealt with the fact that bolts can withstand significantly less cyclic loading than steady loading. We are now looking at the mechanics of why bolts fail if flanges are allowed to separate during operation.
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January/February 2011 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
A continually frustrating phenomenon to many of us is the situation where a tight bolt will function satisfactorily, but in the same situation, a loose bolt will fail...
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May/June 1999 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
In two previous issues we discussed the important difference between steady and cyclic loading, and why loose bolts fail while tight ones do not. This issue will offer two suggestions for reducing the tendency for bolts to become loose.
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January/February 1999 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
In the previous issue, we dealt with the fact that bolts can withstand significantly less cyclic loading then steady loading. We are now looking at the mechanics of why bolts fail if flanges are allowed to separate during operation.
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July/August 1998 Inspectioneering JournalBy Del Underwood at Det Norske VeritasIn a past issue, we discussed one solution to the instrument line block valve pendulum problem. This was where the valve assembly can be mounted remotely from the vibrating product line, such as at-grade. This issue covers two possibilities where the valves need to remain close to the vibrating line.
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July/August 1997 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
In a past issue, we discussed one solution to the instrument line block valve pendulum problem. This was where the valve assembly can be mounted remotely from the vibrating product line, such as at-grade. This issue covers two possibilities where the valves need to remain close to the vibrating line.
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March/April 1997 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
Continuing with the theme "a billiard ball on the end of a fly rod," this month we will look at one alternative to mounting a heavy block valve on a small diameter nipple in vibrating conditions. A popular situation is where the purpose of the...
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January/February 1997 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
There are a number of terms to describe commonly experienced problem conditions with reciprocating compressors. One of the terms that I have always appreciated is the pendulum action of a large unsupported mass on the end of a vibrating pipe.
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May/June 1996 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
This final issue on gusset problems will discuss why gussets are "stiffeners" rather than "strengtheners." The effective load bearing capacity of a member of given strength is based upon how large a cross-sectional area is carrying the load. Gussets are commonly welded to tubular members to reduce their flexure under a bending load.
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January/February 1996 Inspectioneering JournalBy Del Underwood at Det Norske Veritas, and Tim Munsterman at Det Norske Veritas
Last issue, in keeping with the evaluation that "gussets are stiffeners, not strengtheners," we discussed welding around the ends of the gusset plate instead of just along the sides in order to reduce the stress concentration. A further improvement in the gusset life can be obtained by welding it to a reinforcing plate and/or a fitting instead of directly to the pipe.
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September/October 1995 Inspectioneering JournalBy Del Underwood at Det Norske Veritas
A key to any piping evaluation program is to understand where problems can occur. Vibrating piping can propagate a crack relatively quickly. Have you ever installed gussets to stabilize a vibrating pipe situation only to find, shortly thereafter, that the gussets have cracked the pipe? If so, you've got lots of company.
