Sigma Fasteners

Manufacture and Distribute Fasteners for Energy

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Sigma Fasteners

Socket Head Cap Screws

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Socket Head Cap Screws
Socket Head Cap Screws

Standard and custom manufactured socket head cap screws.

Standard Socket Head Cap Screws

Sigma distributes quality fasteners – socket head cap screws, metric socket screws, flat head socket screws or button head socket screws. Also known as Allen head cap screws.

Custom and Modified Socket Head Cap Screws

If you specification requires a modified or custom socket head cap screw Sigma will deliver.

ASTM Material Selection Chart B7, B7M, L7, L7M, 660, 718 Inconel, 17-4 ph, MP35N

Available coated, plated and plain.

Heavy Hex Bolts

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Heavy Hex Bolts 

Heavy Hex Head Bolt
Heavy Hex Head Bolt

There are several ASTM bolting specifications that require a heavy hex head – larger than a standard or finished hex head. These specifications include: A193, A320 and A307B. Although A325 and A490 bolts also require a heavy hex head, they refer to Structural Bolts for dimensional specifications, since structural bolts have shorter thread lengths than standard heavy hex bolts. 

Heavy Hex Bolts are used in a varity of OEM equipment and can be manufactured in multiple ASTM grades. 

ASTM Material Selection Chart  

Check Out Heavy Hex Bolts our Bolt Catalog for Sizes and Dimensions.

Nitronic 60 Bolts

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Austenitic Stainless

Nitronic 60 Bolting

Nitronic 60 is truly an all purpose metal. This fully austenitic alloy was originally designed as a wear alloy, and subsequently has good high temperature properties for temperatures around 1800ºF. The oxidation resistance of Nitronic 60 is similar to Type 309 S.S., and far superior to Type 304S.S.

Material Selection

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Suggested materials for use in various temperatures and atmospheres typically encountered in the energy industry


ASTM
Design-
tion		 Grade Service
Temp-
erature
Range		 Strength and Ductility Suitable
Nuts
(ASTM/
Grade)
Tensile
Min.
psi		 Yield Reduction
of Area
R/A		 Elong-
tion
EL		 Alloy
Type		 AISI
ASTM A-193 B7 High Temp.
from 0 –
480ºC		 125,000 100,000 50 16 Cr-Mo (4140) A194 Gr 2H
ASTM A-193 B16 High Temp.
from 0 –
550ºC		 125,000 105,000 50 18 Cr-Mo V (4140M) A194 Gr 4
ASTM A-193 B7M High Temp.
from 0 –
450ºC		 100,000 80,000 50 18 Cr-Mo (4140) A194 Gr 2HM
ASTM A-320 L7 Low Temp.
-100ºC		 125,000 105,000 50 16 Cr-Mo (4140) A194 Gr 4 or
A194 Gr 7
ASTM A-193 B5 Up to 815ºC 100,000 80,000 50 16 5% Cr (501) A194 Gr 3
ASTM A-193 B6 Up to 450ºC 110,000 85,000 50 16 13% Cr (410) A194 Gr 6
ASTM A-193 B8 Low Temp.
-200 – 650ºC		 75,000 30,000 50 30 18% CR –
8% Ni		 (304) A194 B8
ASTM A-193 B8M Low Temp.
-200 – 750ºC		 75,000 30,000 50 30 16%Cr –
10% Ni		 (316) A194 B8M
ASTM A-320 B8 Low Temp.
-200 – 650ºC		 75,000 30,000 50 30 18% Cr –
8% Ni		 (304) A194 B8
ASTM A-320 B8M Low Temp.
-200 – 750ºC		 75,000 30,000 50 30 16% Cr –
10% Ni		 (316) A194 B8M
ASTM A-320 B8T Low Temp.
-200 – 650ºC		 75,000 30,000 50 30 13% Cr (321) A194 B8T6
ASTM A-320 B8C Low Temp.
-200 – 650ºC		 75,000 30,000 50 30 18% CR –
8% Ni		 (347) A194 B8C
ASTM A-193 B8M
class 2		 Low Temp.
-200 – 650ºC		 125,000 100,000 35 12 16% Cr –
10% Ni		 (304) A194 B8C
ASTM A-453 660 High Temp.
up to 750ºC		 130,000 85,000 18 15 High Iron
Superalloy		 660 (A286) A453 600
ASTM A-564
(cond. 900)
(cond. 1100)		 630 Med Temp.
up to 316ºC		 190,000
140,000		 170,000
115,000		 40
45		 10
14		 Precipitation
Hardening
STST		 630 (17-4) A564 630
ASTM B-408 800 –
800H		 High Temp.
540ºC – 815ºC		 80,000 35,000 25 Incoloy — ASTM B408
ASTM B-164 405 High Temp.
to 815ºC		 85,000 50,000 15 Monel — —
ASTM B-164 K500 High Temp.
650ºC – 423ºC
Low Temp.
650 ºC – 253ºC		 100,000 70,000 35 Monel — —
600, 625, 718, x750 ASTM B446, B637 High Temp.
from 850ºC – 1090ºC		 100,000 80,000 30 Nickel Superalloy (Inconel) — —
B, C, X High Temp.
to 850ºC		 170,000 115,000 30 Nickel Superalloy (Hastalloy) — —
Incoloy 925 High Temp.
to – 1000ºC		 176,000 120,000 40 24 Nickel Iron Chrome — —

Stud Bolts

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Stud Bolts

Stud Bolts
Stud Bolts

Stud bolts are available in ASTM Grades B7, L7, B16, B16M, L7M, B8, 660 and B8M; they are also available exotic metals such as Monel, Titanium, Inconel, Alloy 20, and Hastelloy, 17-4PH. These studs are also available with industrial coatings such as SermaGard, Xylan, PTFE, Fluoropolymers and other coatings.

Stud Bolts for Pressure-Temperature Piping

  • Continuous Thread Studs (Fully Threaded Studs)

Stud bolts are threaded end to end and are often used for flange bolting with two nuts on either end.

There are two types of these studs.

  • Type one – usually for general purpose; the length of stud is measured from end to end. Threads are UNRC-2A.
  • Type two – studs for high temperature pressure piping. These studs are made to dimensional standard requirements of ANSI B16.5 the length of this stud is measured from first thread to first thread, exclusive of points. Threads are UNRC-2A for sizes 1 inch and under and 8 UNR-2A for sizes over 1 inch. The length of stud bolt, measured parallel to the axis, is the distance from first thread to first thread. First thread is defined as the intersection of the major diameter of the thread with the base of the point.

Double End Stud Bolts

Tap End Stud Bolts

ASTM Material Selection Chart

Double End Studs

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Double End Studs – Double ended studs

Double End Studs Bolts
Double End Studs

At Sigma Fasteners we provide mission critical bolting products for the nations leading manufacturers of pressure control equipment for controlling pressures during drilling and oil production.

Double-end studs used by many of these manufacturers have equal-length threads on each end to accommodate a nut and are threaded to a Class 2A fit. Length of stud is measured overall. Both ends have chamfered points, but round points may be furnished on either or both ends at the manufacturer’s option, This style is furnished in the same four types listed for tap-end studs. Double-end studs are used for flange bolting or other applications where torching from both ends is necessary or desirable.

Most steel grades not heat treated or quenched and tempered can be furnished on special order for production quantities. Only the Type 2 continuous thread studs made to specification ASTM A193 grade B7 are stocked in a full range of sizes.

ASTM Material Selection Chart B7, B7M, L7, L7M, 660, 718 Inconel, MP35N