Screws
Hex
Head Cap Screws
There are several differences
between hex head cap screws and hex bolts. The main
one is that cap screws have a tighter body tolerance
than bolts. For example a 1" diameter cap screw
has a maximum body diameter of 1.000, while a 1"
diameter bolt could range as high as 1.022 and may be
as large as 1.060 directly under the head. Hex heads
in nickel-based alloys tend to have a body diameter
larger than the nominal bolt diameter for two reasons.
First, the raw material is generally oversized. Second,
the forging process can create a swell under the head.
A bolt can be turned
or ground to achieve cap screw tolerances. However this
adds to the cost and in the case of a non-stock item
will add to the lead-time. Our experience has been that
bolts tolerances are sufficient most of the time. Therefore
we supply bolts unless a customer informs us the cap
screws are absolutely necessary.
Nickel Systems maintains
an inventory of hex bolts in Hastelloy® (Alloys
C276, C22, B2), Alloy 20 (Carpenter 20®), 18-8 Stainless,
and 316 Stainless in stock at all times. Other alloys
that we currently have hex bolt inventory include Alloy
200 (Nickel 200), Alloy 600 (Inconel® 600), AL6XN®,
Duplex 2205, Ferralium® 255, 330 Stainless and 410
Stainless.
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