Start here: INCONEL® alloy 718
A description, plus links to Technical Bulletin & Technical Papers for use in corrosive & high temperature environments.
http://www.specialmetals.com/products/inconelalloy718.htm

Also, try ASME B31.4 Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids for starters.

You should also look into NORSOK.  This is the Norwegian Oil and Gas standards.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

Try www.ihs.com

Regards from Barcelona
G. García

Wellheads under API 6A have an addendum called API 6A718 specifically written for 718 components to assure avoidance of harmful and brittle second phases, due to field failures.

kat,

Some history: (from http://www.us.cbmm.com.br/english/sources/uses/inconel.htm )

The History of Inconel 718


This venerable alloy was developed by International Nickel (INCO) at its research laboratories in Suffern, New York and at its plant in Huntington, West Virginia in 1959. Niobium was added to increase the alloy's strength at high temperatures. The strengthening mechanism is precipitation of an intermetallic compound (Ni3Nb) in the nickel matrix during heat treatment. Although there were other alternatives to niobium as a strengthener, niobium was found to be unique in its ability to avoid strainage cracking during fabrication of the final components, especially during welding. Because niobium provides a slower aging response, parts can be thermally stress-relieved before they crack.

A decision made in January, 1965, committed General Electric and the industry to focus a significant part of their resources over the next decade to making Alloy 718 work in all its forms, and to become the backbone of the superalloy business. This alloy had been selected as the material for GE's new family of engines called GE-1 (which became the core of the military TF39 and the commercial CF6) and GE-4 (Super Sonic Transport Program).

Even with the urgent need for an improved superalloy for aircraft gas turbine engines at the time of alloy 718ís introduction, it still took five years for this alloy to be approved as turbine material. In addition, it was not until the late 70s and early 80s that 718 became the most important superalloy used in aircraft engines. This development resulted from the African cobalt supply crisis that caused an order of magnitude increase in the price of cobalt from (US$3/lb to almost US$30/lb). As a consequence, cobalt-based alloys which were alternatives to 718 were de-emphasized.

In the course of the first five years of development, several alloys competed for ascendancy until alloy 718 emerged as the winner. In addition to its outstanding capabilities, Alloy 718 was given a great advantage over its competitors by INCO's free licensing policy, which enabled everyone to participate on an equal footing. As such, the resources of the whole superalloy community, producers, users, universities and government laboratories were concentrated and brought to bear on making alloy 718 a mature engineering material. When this happened, the applications and production exploded and alloy 718 became the mainstay alloy of the Gas Turbine Era.

One of the materials competing with Alloy 718 in the early days was Udimet 630 developed by Special Metals Corporation. This alloy was very similar to alloy 718, but contained more niobium (6.5wt%). Alloy 718 was eventually chosen over Udimet 630 for the turbine disks, mainly because of its widespread availability (because of INCOís policy) and extensive data base compared to Udimet 630, that was single sourced.

_MJC

  

kat6787,

Why are you using Inconel 718 bolting materials for a
"subsea" application ? Why not MONEL K-500 which was developed for this purpose ?

Inconel 718 is better suited to aerospace, high temperature applications. Why is this material being used in this application ? Does MONEL not have the necessary strength ?


_MJC

  

Iconel 718 was specifically asked for in this case. I am a new engineer and my background is not metallurgy or material science, so I wanted to find out as much as I could about the materials being used. I'm don't know why 718 was chosen, but I wanted to find out what I could about it, in case I was asked questions about it.

Thanks to everyone for the help.

Cheers,
Kat

Just for your info, 718 isn't the most resistant alloy when it comes to the loading of notched samples in a high chloride environment.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

thread338-18000

Inco 718, although not the best alloy in marine applications (better suited to aerospace applications withh high temps) may have been specified for the bolt material as the alloy is very well known in fastener applications, so shear behavior, stress rupture and fatigue characteristics are all well known. Much less so for Monel 630. Production costs of special bolts in Inco 718 may well be lower and standard bolts in Inco 718 will be more readily available off-the-shelf.