Category Archives: Subsea

Cathodic Corrosion Protection Of High Strength Subsea Bolting

In the last decade Hague Fasteners have seen massive growth in the supply of British Manufactured, European origin material Critical Bolting manufactured to Aker, VGS and other OEM specifications specifically written to ensure the Prevention of failures of high strength fasteners in use in offshore and subsea applications.

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The selection, specification, manufacture and installation of fasteners for subsea use is critical to ensure their resistance to corrosion due to various forms of environmentally assisted cracking.

As Oil exploration progresses into far deeper waters, the cost of a fastener failure or other mechanical component breakdown is both a serious financial risk but more so the environmental damage could be truly catastrophic.

With reputation at stake, Hague Fasteners with 45 years of sector experience and technical excellence ensures your subsea projects are without risk and quality assured.

The Subsea specifications Hague Fasteners work strictly too give particular emphasis on the prevention of environmentally induced cracking under the conditions of cathodic prevention. Cathodic protection is frequently used in Marine vessels, and offshore and subsea steel structures to reduce the base metal corrosion by making it the cathode in an electrochemical cell.

It is Hague’s decades of experience and knowhow that gives their ever growing Subsea customer base the peace of mind that the special fasteners manufactured and coated by Hague Fasteners do not deviate from the expert specifications designed to minimise the risk from the various forms of environmentally assisted cracking (EAC).

These include stress corrosion cracking (SCC), hydrogen embrittlement (HE) and sustained load cracking (SLC).

The sectors supplied by Hague Fasteners are almost always the high performance applications requiring higher strength fasteners. A major issue with fasteners used offshore and subsea is that higher strength fasteners are susceptible to stress corrosion cracking and hydrogen embrittlement. In general, higher the strength, the higher the hardness of the material and the greater the susceptibility to these failure mechanisms.

The more common critical offshore and subsea bolting material grades requested are the common bolting materials ASTM A 320 Grade L43, ASTM A320 L7 and ASTM A193 Grade B7, the fastener industry is flooded with inferior imported mass produced petrochemical fasteners where quality is often compromised in exchange for being the cheapest and securing contracts. Hague Fasteners distance themselves from this side of the market as failures in these cheap and suspect quality items have occurred, particularly where the use of cathodic protection increases their susceptibility to hydrogen cracking.

Hague Fasteners certify their manufactured items with additional PMI testing, MPI testing and further ensure integrity of their components by limiting the hardness well below the proven 34 HRC where high strength bolting becomes highly susceptible to cracking from hydrogen embrittlement induced by cathodic protection. For reference, the maximum hardness of regular B7 is 35 HRC and hence can fall above the susceptible range.

Quality simply can not be compromised. The best in British manufacturing at Hague Fasteners ensures all the risks are assessed and minimised by strict adherence to Subsea and Offshore manufacturing specifications. Where reputation is at stake, Hague Fasteners are your solution.

Nickel Alloy Special Fasteners

Nickel Based Alloy Fasteners are used in a wide range of Global Industries.

Hague Fasteners have been a major manufacturer of the more specialist bolting components used for Subsea Engineering & Oil & Gas sectors, particularly the production and supply of small batch quantities of special fasteners to Customers Drawings.

Nickel Alloy Fasteners

The wide range of superalloys Hague Fasteners manufacture include:-

Alloy 600 – Inconel 600 – BS 3076 NA14 – Wekstoff 2.4816 – ASTM B166 – UNS N06600
Alloy 601 – Inconel 601 – Werkstoff 2.4627 – ASTM B166 – UNS N06601
Alloy 625 – Inconel 625 – BS 3076 NA21 – Werkstoff 2.4856 -ASTM B446 – UNS N06625
Alloy 718 – Inconel 718 –  Werkstoff 1.4668 – ASTM B637 – UNS N07718
Alloy 750 – Inconel 750 –  Werkstoff 2.4669 – ASTM B637 – UNS N07750
Alloy 400 – Monel 400 – BS 3076 NA13 – Werkstoff 2.4360 – ASTM F467  – UNS N04400
Alloy K500 – Monel K500 – BS 3076 NA18 – Werkstoff 2.4375 – ASTM B865-04  – UNS N05500
Alloy C276 – Hastelloy C276 – Werkstoff 2.4819  – ASTM B574  – UNS N10276
Alloy 22 – Hastelloy C22 – Werkstoff 2.4602  – ASTM B574  – UNS N06022
Alloy B2 – Hastelloy B2 – ASTM B335  – UNS N10665
Alloy X – Hastelloy X – Werkstoff 2.4655 – ASTM B572  – UNS N06002
Alloy B3 – Hastelloy B3 – ASTM 2.4600 – ASTM B335 – UNS N10675
Alloy G30 – Hastelloy G30 – Werkstoff 2.4603 – ASTM B581  – UNSN06030
Alloy 50 – Nitronic 50 – ASTM A479 XM19 – UNS S20910
Alloy 60 – Nitronic 60 – ASTM A193 B8S – UNS S21800
Alloy 75 Nimonic 75 – Werkstoff 2.4951 – ASTM B637 – UNS N06075
Alloy 80A – Nimonic 80A – BS 4882 NA20 – Werkstoff 2.4952 – ASTM B637  – UNS N07080
Alloy 90 – Nimonic 90 – ASTM B408  – UNS N07090
Alloy 800 – Incoloy 800 – BS 3076 NA15 – Werkstoff 1.4876 – ASTM B408  – UNS N08800
Alloy 800H – Incoloy 800H – ASTM B408
Alloy 800 HT – Incoloy 800HT – Werkstoff 1.4959 – ASTM B408 – UNS N08811
Alloy 825 – Incoloy 825 – BS 3076 NA16 – Werkstoff 2.4858 – ASTM B425 – UNS N08825
Alloy 925 – Incoloy 925 – ASTM B805  – UNS N09925
Alloy DS – Incoloy DS – BS 3076 NA17 – Werkstoff 1.4862 – UNS N08330

MP35N Fasteners

MP35N Special Fasteners Focus For Subsea & Offshore Oil and Gas Engineering.

MP35N (Ni Co Cr Mo 35 35 20 10)
is a nickel-cobalt base alloy that is often specified in subsea special fastener designs due to its unique combination of properties – ultra high strength, toughness, ductility and outstanding corrosion resistance.

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Hague Fasteners’ manufactured critical special fasteners are, by virtue of the alloy, work strengthened and finally aged to obtain strength levels of 260 to 300 ksi (1793-2086 MPa) in its full strength condition. With less cold work reduction, the alloy has the best balance of strength and stress corrosion cracking resistance (SCC) for harsh environments.

Hague’s MP35N custom fasteners resist corrosion in hydrogen sulfide, salt water and other chloride solutions, as well as the mineral acids (nitric, hydrochloric, sulfuric). In addition, all critical manufactured special fasteners exhibit exceptional resistance to crevice corrosion cracking in seawater and other hostile environments hence being a popular choice for high integrity applications in offshore and subsea industries.

HEAT TREATMENT (AGING)
MP35N should be aged at the temperature required to achieve the final properties desired. The amount of cold work in MP35N defines the recommended aging treatments.

For AMS 5844 (full strength/ heavily cold worked) material, the alloy should be aged at 1000°F – 1200°F for 4 hours.

For optimum sulfide SCC resistance, less-heavily cold worked material can be aged at 1300°F or 1350°F for 4 hours or at 1425°F for 6 hours as indicated in NACE MR-0175. The 1425°F aging treatment provides the best sulfide SCC resistance, but at the expense of strength.

Exposure to temperatures much above the recommended aging temperatures may result in a significant (and non-recoverable) loss in strength caused by the reversion of the cold-worked metallurgical structure to the much softer annealed structure.

Hague Fasteners are manufacturing every type of conceivable special fasteners and turned components for use in Downhole pump drive shafts assemblies and associated tooling.
High strength special fasteners for marine components.
Seawater Valve stems and pump shafts in Oil & Gas sector and desalination systems.
Fastener system components – pins, tension bolts, shear bolts, engine bolts, tie rods and all critical high integrity corrosion resistant bolts.
Miniature fasteners and micro screws for Medical applications – bone plates, screws, pins.
Fastener Components for use in Autosport & Aerospace.

SPECIFICATIONS
MP35N
AMS 5758
AMS 5844
AMS 5845
ASTM F562
ASTM F688
NACE MR01-75
ISO 15156

UNS S31254 Fasteners

The high integrity bolts and special fasteners that Hague Fasteners manufacture are often installed into highly aggressive environments.

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Anti-corrosion materials are therefore commonly specified where reliance on a surface coating is simply impractical.

The 6% Mo Duplex Stainless Steel materials are among the best stainless steels for use in water and seawater giving excellent service in some very aggressive environments.

This various special fasteners including Hex Bolts, Eng Studs, Studbolts, Hex Nuts and Socket Capscrews Hague manufacture in 6Mo (254Smo) stainless are often specified due to the following characteristics:

• Comparable pitting and crevice corrosion resistance (PREN > 40, akin to SuperDuplex Fasteners.
• Excellent resistance to strong acids.
• Excellent stress corrosion cracking resistance.
• Higher yield strength than standard stainless steels available in Class 70 and Class 80 Cold Worked strength grades.
• Good impact toughness at sub-zero temperatures (even tougher than SuperDuplex grades).
• A cost effective alternative to some of the more expensive nickel base superalloys.

Hague Fasteners are manufacturing all types of UNS S31254 Special Fasteners and supplying global industry sectors such as:

Pulp and paper, Water Desalination Facilities, chemical processing plant, chemical tanker transportation, heat exchangers & Tubing Condensers, metal refining, flue gas desulphurisation (FGD), structural subsea fastener components, offshore oil and gas equipment, submarines & aggressive food processing manufacturing lines.

Whatever your application, whatever your design, you can trust Hague to manufacture and deliver Special Fasteners on time.

Alternative Specifications include:-
254SMO, 6Mo, 6% Mo, 1.4529, 1.4547, N08926, UNS S31254, Duplex

Subsea Fasteners

Offshore Subsea Fasteners

The offshore oil & gas industry is one of the largest industry sectors Hague Fasteners service with their British Manufactured High Integrity Special Fasteners.

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Hague Fasteners offshore oil and gas bolting are often used for high integrity systems where the reliability and critical quality are essential for the long term performance of the structures they are fitted to, none more so when used as structural components and for high pressure vessels and piping.

As with all of Hague Fasteners precision manufactured components it is of critical importance that the Custom Fasteners and Superalloy Bolting are manufactured, without deviation, to the Original Equipment Manufacturers designs that provide for the required service life for the various exposure and service conditions they are designed and exposed to.

Bolting can fail for a number of reasons (e.g. overload, fatigue or corrosion). The materials selection, manufacturing methods, bolt fabrication, protective coating and the installation are all critical and need to be strictly adhered to, thus ensuring that long service performance is guaranteed. The actual service conditions and the external environment impact and maintenance will subsequently determine the service life of the bolting.

With over 40 years of Subsea Engineering experience Hague Fasteners turns your critically specified designs and drawings into High Integrity Quality Assured bolts ready to fit and install within hours where necessary. Hague Fasteners original concept of a”Breakdown Delivery Service” is as real today as it was 40 years ago.

Whatever the material, whatever the design, whatever the delivery, Hague Fasteners is your solution.

Embracing your designs
Conforming materials selection
Respecting corrosion protection
Leading Customer Service

Hague Fasteners Limited – Global Subsea Bolting Solutions (Since 1971).

Plant Investment for Special Fastener Subsea Marketplace

Hague Fasteners are thrilled to take delivery of their new 4 Axis Machining centre to add extra capacity to their ever increasing workload.

This is the 2nd phase of significant plant investment as Hague Fasteners continue to grow as they service new Export and UK markets.

A significant growth this year into the Subsea marketplace has seen particularly complex milled fasteners being regularly manufactured to Customers drawings and supplied through Scotland, Norway and throughout Benelux.

Managing Director, Jon Hague, explained “with the successful implementation of the 2013 Special Fastener Engineering Young Apprenticeship scheme the flexibility amongst our new young workforce is enabling us to make rapid Plant acquisitions to further improve the delivery times and variety of complex components we can offer our ever growing number of Global Customers.”


Hague Fasteners continue in the proud footsteps of their founder, they are still a Private Company owned now by the 2nd Generation of the Hague Family. The Company structure and strong financial position the Company enjoy, in their 5th Decade of Bolting Production, ensures needless bureaucracy does not inhibit the firms continued growth.

Hague Fasteners have always led from the front, opportunities are identified and the business plan tweaked accordingly to always ensure that Hague Fasteners are the rapid solution to bolting supply issues around the world.