Certification letter for water tank support stand

[charliealphabravo]

Hi guys,

From time to time our company provides design support and certification for manufactured components like plastic pipe stands, steel supports for plastic water tanks, etc. Mostly the mechanical engineers deal with this but I sometimes get pulled in on the structural aspects.

Typically I am used to designing structures with a physical address. There is a certain comfort in knowing that the structure will not be mass produced, used by an unknown third party, or move from where I last saw it.

My question is along the lines of how mechanical engineers control their liability on manufactured components such as I have described where certification may be in the form of a letter that will be posted on the manufacturer's website.

1. How do you control the liability that grows as the number of manufactured components and end users grow into the 100s or 1000s?
2. Is it appropriate for certification letters to have an expiration of say 4 years to account for code cycles or the death/retirement of an engineer?
3. What resources describe the appropriate information that should be included in a calculation report or certification letter?
4. Is it appropriate to defer certain aspects of the design/selection to others. In the example of the water tank stand how do you specify or defer the design/selection of the base and possible base anchorage which may be on many different types of soils or surfaces or perhaps a skid?

There are probably other aspects that will occur to me but enough for now. I'm just looking for resources so that I can critically/independently assess the mechanical projects that I may get involved in.

TIA

 

[bimr]

A certification letter is a document certified by a competent authority that the supplied good or service meets the specifications that it was designed to. Also called a certificate of conformance, certificate of conformity. Nothing more, nothing less.

 

[JStephen]

#1 would hopefully be covered by product liability insurance.
#2, I believe the better approach is to certify that it was designed, per standard XYZ of year 2015 or whatever and leave it at that. That doesn't certify that it was designed for all loads for all times.
#3, in the cases I'm familiar with, the applicable standard describes what goes in the certification (which is a certification of compliance with the standard).
#4, yes, and I assume for seismic loading, that's what you'd have to do. That is, say it's designed for these certain conditions at this location based on this standard, and use anywhere else will require reconsideration.