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This post is an extension of my project to dampen the dynamic response of a 1/2"dia stainless steel tube x 40" span in a clamped-pinned configuration that fails in fatigue after 2 years operation. So far the composite manufacturers I have contacted don't determine damping coefficients for their...

A British Firm (GL Industrial Services UK Ltd.) was experimenting with composites to dampen the dynamic response of small bore connections to compressors with the handle "Constrained Layer Damping". This investigation was completed in 2019, but the Final Summary Report is a little sparce on...

Thanks Greg, I received an E.Mail notification with your response which included the following statement at the end: "You don't have to wrap the whole tube evenly, the maximum bending and least impact from the mass loading is at the root." This statement does not appear in the text...

Thanks Greg Locock, This 40" length of tube is responding to a process pulsation that caused the tube-to-nozzle weld (at the anchored end) to fail in fatigue after 2 years of continuous operation that subsequently caused loss of production to make the repair. The 40" span is not close to walls...

My apologies - trimmed the Rules by accident.

Let me know if you agree with my equations and whether the incremental wrap produced the result expected, thanks.

A consult with the tank manufacturer revealed that this cutout should have been filled with grout before the original hydrostatic test back in 1978 ! That's quite a testimony to the conservatism in API 650.

I would like to determine the effect on natural frequencies in bending by adding incremental layers of a composite wrap to the entire length of a stainless steel tube. For this application, the tube is simply supported at one end and anchored at the other with uniformly distributed mass of just...

Question for any Storage Tank Stress Analyst out there: "Do you know the basis for the limiting dimensions in API 650 Annex O Table O.1a or b?

HTURKAK, to you points: - My tank has no bridging beam - API 653 Inspection has been performed - The recommended API 653 repair involves a "major alteration" involving jacking up the tank, cutting out the entire bottom plate covering the 36" x 12" cut-out including the 3"nps draw-off piping and...

HTURKAK and Dhurjati Sen, I have attached the Drawing for discussion. I fitted a polynomial curve to the dimensions in API 650 Table O.1 and most drawing dimensions agreed when extrapolated to 3"nps.

Dhurjati Sen, As described in my post there is "some minor pitting on the underside of the floor plates, which have been patched", which includes the bottom plate over and adjacent to the "cut-out" area. The reason for external annular ring thinning is organic growth in soil caught in the grout...

HTURKAK, Instead of a ring wall with an "opening", this tank has a 5 foot thick reinforced concrete slab, which is why I call the missing concrete a "cut-out". Figure O.1 of API 650 indicates a beam bridging the ring wall "opening" located inside the tank, however my tank does not have this...

A 40ft x 32ft high diesel storage tank at my plant has provided excellent service since 1978 with some minor pitting on the underside of the floor plates, which have been patched. Recently, localized thinning below 0.1" of the 0.25" outer annular ring (chine) adjacent to the 12" wide concrete...

3D & Ed, Testing was completed as described resulting in no appreciable difference in neodymium/plastic epoxy bond strength at north or south poles. All that is coincidental may not be causal.

Thoughts from a Chemist; I'm a bit confused by 3DDave's comment about silicon oil contamination...why would neodymium magnets have silicon oil only on one side? Why would silicon oil be there at all? I thought these magnets were just small, flat cylinders of a neodymium alloy. If these are...

3D and Ed, You've convinced me to experiment. Please suggest any steps I have missed below. 1) purchase 10 neodymium magnets 2) clean both surfaces thoroughly with duct tape then acetone 3) line up magnets in a row on clean sheets of paper, facing 5 north and 5 south up, 4) mix J-B KWIKWELD...

3DDave, The silicon contaminant would have been spread over both sides of the 16 magnets. They were handled excessively with bare fingers befoe being assigned to the current project. More 'controlled' testing is in order. prex and Ed, Would'nt steel reinforced resin be a good idea if it...

3DDave, No de-grease was applied to ANY of the magnets.

Is there any possibility that the 'correct' magnetic flux can improve the epoxy bonding process (since the opposite seems to be happening).