heavy hex bolts
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Heavy Hex Bolt

We are the Roll-Fast leading manufacturers of Heavy Hex Bolt for the construction of Petrochemical Industries & general maintenance work on a daily basis. We offer Heavy Hex Bolts in different grades like 8, 10, 12, B7, B7M, B16, B8, 307A etc. We offer sizes from M10 to M100 or 1/2” to 4”. There are numerous grades and the heavy pattern is typically used for large diameter and high strength bolts.

What is Heavy Hex Bolts?

The Heavy hex bolt are same as standard bolts, main difference is width across flat & head thickness is larger than standard bolts. Heavy Hex Bolts are bolt fasteners with six-sided hexagon head and externally threaded full or partial body. Hexagonal head profile enables easy wrenching while putting enough torque to the bolting joint. Hex bolts are used with hex nuts or a tapped hole.

The Heavy Hex Bolts following EN 14399-4, DIN 6914, Dast 021, ASME B18.2.1, ASME B18.2.6, ASTM A490 is to use heavy structural system & flange for obtain the required strength and heavy jerk loading capacity of the threads within the nut. The heavy hex bolt assembly is used in both preloaded and non-preloaded applications and it can be argued that in the event of failure by thread plastic deformation the assembly still acts as a non-preloaded assembly. These assemblies are more sensitive to over-tightening during preloading and therefore require more site control. If severely over tightened during preloading the mode of failure by plastic deformation of the engaged thread of the bolt assembly offers little indication of impending failure.

These Heavy Hex Bolt are manufactured by us in Alloy Steel, carbon steel, stainless steel & Duplex Steel. Popular carbon steel grades include A 194 and A 320. Grades include B7, B7M, B16, B8, B8M, (Class 1 and 2), A2-50, A2-70, A2-80, SS 316, SS 316S 31 etc. The requirements for these are mentioned in the American standard A 194 and A 320.

Roll-fast manufactures world class Heavy Hex Bolt for use in petrochemical industry, these bolts are manufactured as per Indian, European and American standard in Coating like Plain, Black and Hot Dip Galvanised (HDG), Geomat, Zinc Flake, Zinc Electroplating, Xylon, PTFE, Non-Metallic coating etc. .

Heavy Hex Bolts are used with Hex Nuts to extensively in petrochemical projects for flange joints in high temperature pipelines and also on rigs and offshore platforms in various parts of the world. Some of the major grades and sizes manufactured are given below-

Grade

Diameter

Type

Application area

ASTM A 193 Gr. B7, B7M, B16, B8

1/2" to 4"

M10 to M100

Ferratic steel

high temperature piping, flange joints, rigs and offshore platforms

8.8, 10.9, 12.9

1/2" to 4"

M10 to M100

Ferratic steel

high temperature piping, flange joints, rigs and offshore platforms

SS 316 / AISI 316, A2-50, A2-70

1/2" to 4"

M10 to M100

Ferratic steel

high temperature piping, flange joints, rigs and offshore platforms

SS 316 L / AISI 316 L

1/2" to 4"

M10 to M100

Ferratic steel

high temperature piping, flange joints, rigs and offshore platforms

316S311

1/2" to 4"

M10 to M100

Ferratic steel

For low temperature piping, flange joints and platforms

Threads are standard right-hand and unified inch coarse series (UNC, Unified National Coarse) or Unified inch fine (UNF, Unified National Fine). Also metric thread with Right & Left-hand threaded Hex Bolts are also available.

To ensure full thread engagement with the hex nut, bolts/screws should be long enough to allow at least two full threads to extend beyond the nut face after tightening. Conversely, there should be two full threads exposed on the head side of the nut to make sure the nut can be properly tightened.

Manufacturing

We manufacture Structural Bolts in bigger diameters from M-16 to M-100 in diameter in class 8.8 and 10.9, stocks are readily available and we are manufacturing bolts diameter from M-16 to M-100 diameter, we also offer ISO threads and nominal thread fitments. The biggest advantage of our manufacturing is that we do thread rolling after heat treatment, this provides for extra torque and extra fatigue strength by more than 50% and also ensures stronger unbroken fiber lines and a very fine marten site in core and in the threads of the bolts.

These Bolts are first cut on Bandsaw cutting as per Length required and then we do forging & CNC machining on bolts, we then do heat treatment on them in our factory using an advanced SQF sealed quench heat treatment furnace from DOWA Japan, the heat treatment furnace is SCADA controlled and provides 100% repeatability batch after batch. The heat treatment result is a perfect marten site after hardening and gives perfect results after tempering as per standard requirement. After heat treatment we complete the Thread Rolling and then coating as per customer requirement and then final assembly.

We also manufacturers low carbon bolts in M10 to M100 & 1/2” to 4” in plain, zinc plated and hot dip galvanised finish, we are exporting these Nuts to many countries like USA, Europe and middle east. We also distribute and market the following products in alloy steel, carbon steel and stainless-steel grades for the following products in ASME B18.2.1, ASME B18.2.6, ASME B18.2.6M, DIN 6914, BS 3692 etc.

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