De-rating the strength of bolts due to galvanizing
De-rating the strength of bolts due to galvanizing
(OP)
Hi there,
What are peoples thoughts on de-rating the tensile strength of bolts which have been galvanised?
I am designing multiple flanges which will be assembled using AS4291 / AS1110 Grade 8.8 bolts which will be galvanized. I realise that hydrogen embrittlement generally occurs in bolts with a tensile strength above 1000 MPa, so is it necessary to de-rate bolts with a lower strength than this? Can the galvanising process reduce the strength in any other way?
Thankyou
What are peoples thoughts on de-rating the tensile strength of bolts which have been galvanised?
I am designing multiple flanges which will be assembled using AS4291 / AS1110 Grade 8.8 bolts which will be galvanized. I realise that hydrogen embrittlement generally occurs in bolts with a tensile strength above 1000 MPa, so is it necessary to de-rate bolts with a lower strength than this? Can the galvanising process reduce the strength in any other way?
Thankyou





RE: De-rating the strength of bolts due to galvanizing
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: De-rating the strength of bolts due to galvanizing
RE: De-rating the strength of bolts due to galvanizing
RE: De-rating the strength of bolts due to galvanizing
I was thinking That may be why so many of the MIL specs are based on fancy paint jobs.
RE: De-rating the strength of bolts due to galvanizing
RE: De-rating the strength of bolts due to galvanizing
Correct - the mechanical properties (AS4291 are identical to ISO 898-1)
These flanges are being installed on cement lined pipelines, maximum operating temperature of the water is 50degC so I dont expect the bolts to even reach that.