Category Archives: Technical Bulletins

Technical Bulletins

Duplex and SuperDuplex Material Study

Duplex and superduplex steels are advanced materials that offer superior mechanical, corrosion, and erosion resistance properties over conventional stainless steels. These alloys have a two-phase microstructure consisting of austenite and ferrite phases, resulting in improved strength, toughness, and resistance to stress corrosion cracking. These properties make duplex and super duplex stainless steels ideal for applications in aggressive environments such as the oil and gas, chemical, and marine industries.

SeprDuplex Offshore Installation

Development of Duplex and Superduplex Stainless Steels

Duplex and super duplex stainless steels were developed in the 1930s and 1940s as a result of research into the corrosion resistance of stainless steels in acidic and chloride-containing environments. Early duplex stainless steels were low in nickel and high in chromium and molybdenum to improve their corrosion resistance. However, these alloys had limited toughness and ductility, which made them difficult to fabricate and prone to cracking during welding.

In the 1960s, the development of more advanced duplex stainless steels began, incorporating additional elements such as nitrogen, copper, and tungsten to improve their mechanical properties and welding characteristics. The addition of nitrogen, in particular, increased the strength, ductility, and corrosion resistance of duplex stainless steels, leading to the development of super duplex stainless steels.

Grades of Duplex and Superduplex Stainless Steels

  1. Duplex Stainless Steels (UNS S31803, S32205): These grades contain around 22% chromium, 5-6% nickel, and 3% molybdenum. They also have a small amount of nitrogen (0.1-0.2%) to improve their mechanical properties. Duplex stainless steels offer a good combination of strength, toughness, and corrosion resistance, making them suitable for a range of applications in the chemical, petrochemical, and pulp and paper industries.
  2. Super Duplex Stainless Steels (UNS S32750, S32760): Super duplex stainless steels contain around 25% chromium, 7% nickel, and 3.5% molybdenum, as well as 0.3% nitrogen. These alloys have higher strength and corrosion resistance than duplex stainless steels, making them suitable for use in more demanding applications such as offshore oil and gas production, desalination plants, and chemical processing.
  3. Lean Duplex Stainless Steels (UNS S32304): Lean duplex stainless steels contain around 21% chromium, 4.5% nickel, and 0.3% nitrogen. They offer good corrosion resistance and lower cost than other duplex stainless steels, making them suitable for applications in the food processing, wastewater treatment, and architectural industries.
  4. Hyper Duplex Stainless Steels: Hyper duplex stainless steels are a new generation of duplex stainless steels that offer even higher strength and corrosion resistance than super duplex stainless steels. They contain around 27% chromium, 7% nickel, 4% molybdenum, and 0.8% nitrogen. Hyper duplex stainless steels are currently being developed for use in highly corrosive environments such as offshore oil and gas production and chemical processing.

Trademarked Grades

There are several trademarked duplex and superduplex stainless steel grades that have been developed to meet specific application requirements. Some of the most common ones include:

  1. SAF 2205: This is one of the most widely used duplex stainless steel grades. It contains 22% chromium, 5% nickel, and 3% molybdenum, along with other alloying elements such as nitrogen and manganese. SAF 2205 offers excellent corrosion resistance, high strength, and good weldability, making it ideal for use in a range of applications, including oil and gas, chemical processing, and marine environments.
  2. SAF 2507: This is a super duplex stainless steel grade that contains 25% chromium, 7% nickel, and 4% molybdenum, along with other alloying elements such as nitrogen and copper. SAF 2507 offers even higher corrosion resistance and strength than SAF 2205, making it ideal for use in highly corrosive environments such as desalination plants and offshore structures.
  3. Zeron 100: This is another super duplex stainless steel grade that contains 25% chromium, 7% nickel, and 3.5% molybdenum, along with other alloying elements such as nitrogen and tungsten. Zeron 100 offers excellent corrosion resistance, high strength, and good weldability, making it ideal for use in a range of applications, including oil and gas, chemical processing, and marine environments.
  4. Ferralium 255: This is a super duplex stainless steel grade that contains 25% chromium, 7% nickel, and 3.5% molybdenum, along with other alloying elements such as nitrogen and copper. Ferralium 255 offers even higher corrosion resistance and strength than SAF 2507, making it ideal for use in highly corrosive environments such as desalination plants and offshore structures.
  5. LDX 2101: This is a lean duplex stainless steel grade that contains 21% chromium, 1.5% nickel, and 0.3% molybdenum, along with other alloying elements such as nitrogen and manganese. LDX 2101 offers good corrosion resistance and high strength, making it ideal for use in a range of applications, including chemical processing and marine environments.

Each of these duplex and super duplex stainless steel grades has been developed to meet specific application requirements. For example, SAF 2205 and Zeron 100 offer good weldability, while SAF 2507 and Ferralium 255 offer even higher corrosion resistance and strength for use in highly corrosive environments. LDX 2101, on the other hand, offers a more cost-effective solution for applications where high strength and good corrosion resistance are required but at a lower cost than super duplex stainless steels.

Super Duplex Zeron 100 Fastener Grades

Zeron 100 is further developed in higher strengths graded FG and FLT versions. Hague Fasteners have extensive experience working with these alloys.

Zeron 100 is a duplex stainless steel that is widely used in a variety of industrial applications. It is an alloy that contains a high percentage of chromium, molybdenum, and nitrogen, which provide it with exceptional corrosion resistance properties. It also has high strength and toughness, making it ideal for use in applications where mechanical stresses are present.

The higher strength graded FG and FLT versions of Zeron 100 are modifications of the standard alloy that have been designed to provide even greater strength and durability. These alloys have higher levels of nickel, nitrogen, and molybdenum, which provide them with even greater corrosion resistance and strength. They also have improved toughness, which is essential in applications where high mechanical stresses are present.

The FG version of Zeron 100 is specifically designed for use in fastener applications. It has been optimized to provide the high strength and corrosion resistance required in these applications. The FLT Grade of Zeron 100, on the other hand, is suitable for use in floating production systems, such as oil and gas platforms. It has been designed to withstand the harsh and corrosive environments found in these applications.

The applications of Zeron 100 and its higher strength grades FG and FLT are extensive. The standard alloy is commonly used in the chemical and petrochemical industries, where it is used in equipment such as pumps, valves, and heat exchangers. Its excellent corrosion resistance properties also make it ideal for use in marine applications, such as seawater desalination plants and offshore structures.

Zeron 100FG is commonly used in fastener applications, such as bolts and screws, where high strength and corrosion resistance are essential. It is also used in oil and gas production equipment, such as valves, pumps, and manifolds.

Zeron 100FLT is commonly used in floating production systems, such as offshore platforms. It is used in a variety of equipment, including risers, connectors, and subsea production systems. Its exceptional corrosion resistance and high strength make it an ideal material for these applications.

Zeron 100 and its modified FG and FLT grades are exceptional alloys that provide excellent corrosion resistance, strength, and toughness. They are widely used in a variety of industrial applications and are particularly useful in aggressive and corrosive environments. We work extensively with these alloys, and we are confident that they will continue to play a vital role in the industrial landscape for many years to come.

Environment and Applications

Duplex and superduplex stainless steels are ideal for use in aggressive environments where conventional stainless steels would fail. These alloys offer excellent resistance to pitting, crevice, and general corrosion, as well as erosion and stress corrosion cracking. Some common applications of duplex and super duplex stainless steels include:

  1. Oil and Gas: Duplex and super duplex stainless steels are widely used in offshore oil and gas production, where they are exposed to highly corrosive environments containing chloride, hydrogen sulfide, and carbon dioxide. These alloys offer excellent resistance to corrosion and erosion, making them ideal for use in subsea pipelines, offshore platforms, and other critical components.
  1. Chemical Processing: Duplex and super duplex stainless steels are used in chemical processing plants where they are exposed to highly acidic or alkaline environments, as well as high temperatures and pressures. These alloys offer excellent resistance to corrosion and erosion, making them ideal for use in heat exchangers, reactors, and other critical components.
  2. Desalination: Super duplex stainless steels are commonly used in desalination plants, where they are exposed to highly saline environments containing chloride and other aggressive ions. These alloys offer excellent resistance to corrosion and erosion, making them ideal for use in seawater intake systems, brine concentrators, and other critical components.
  3. Marine: Duplex and super duplex stainless steels are widely used in marine applications, where they are exposed to seawater and other corrosive environments. These alloys offer excellent resistance to corrosion and erosion, making them ideal for use in offshore structures, shipbuilding, and other critical components.

Duplex and super duplex stainless steels are advanced materials that offer superior mechanical, corrosion, and erosion resistance properties over conventional stainless steels. These alloys have a two-phase microstructure consisting of austenite and ferrite phases, resulting in improved strength, toughness, and resistance to stress corrosion cracking. There are several grades of duplex and super duplex stainless steels available, each with different compositions and properties, making them suitable for a range of applications in the oil and gas, chemical, desalination, marine, and other industries. The development of hyper duplex stainless steels represents a new generation of these alloys, offering even higher strength and corrosion resistance properties for use in highly corrosive environments.

Technical Bulletins, Thread Protection

Screw Thread and Bolt Protection

Screw Thread Protection for Engineered Components

Thread Protection

One of the most common forms of damage to engineered components is screw thread damage. Screw threads are an integral part of many components, and any damage to them can have far-reaching consequences. In this article, we will detail the problems caused by damaged screw threads in engineered components commonly caused by poor bolt protection during packaging and shipping.

Screw Thread Protection for Engineered Components

Engineered components are crucial in various industries, from automotive to safety-critical Nuclear and Defence installations. These components are designed to perform specific functions with a high degree of precision and reliability. However, when these components are damaged during packaging and shipping, it can cause significant problems.

The Problems Caused by Damaged Screw Threads

The primary function of screw threads is to provide a secure and reliable connection between components. Any damage to the threads can compromise this connection and result in several issues.

Firstly, damaged threads can cause the component to fail prematurely. When the connection between components is not secure, it can cause the assembly to become loose or dislodged, resulting in a malfunction or failure. This can be particularly dangerous in critical applications, where a single component failure can have catastrophic consequences.

Secondly, damaged threads can result in increased maintenance costs. If a component fails prematurely due to damaged threads, it will need to be replaced or repaired. This can result in increased downtime, lost productivity, and increased costs.

Thirdly, damaged threads can result in reduced efficiency. When the connection between components is not secure, it can result in vibrations, which can cause wear and tear on the component. This can result in reduced efficiency and increased energy consumption.

Bolt Protection

The Extra Efforts Hague Fasteners Go To Protecting Threads and Precision Turned Parts

One such method is by wax dipping them to prevent knocks and damage after manufacturing. Wax dipping is a process where the component is dipped into a bath of hot wax to create a protective coating. This coating provides a layer of protection that can prevent damage from knocks and bumps during shipping and handling. It also helps to prevent moisture and other contaminants from penetrating the component, which can cause corrosion or other forms of damage, giving up to 10 years of extended rust prevention in storage.

Wax dipping is an effective and cost-efficient way to protect engineered components, especially threads, during shipping and handling. By taking this extra step, we can ensure that our components are received in perfect condition, ready to perform their intended function with reliability and precision. This protection is far more effective than the Extruded Mesh Sleeves sometimes applied to threaded parts.

Screw Thread and Bolt Protection, Damaged Threads Summary

Damaged screw threads in engineered components can cause significant problems, including premature component failure, increased maintenance costs, and reduced efficiency. That’s why it’s essential to protect components during shipping and handling to prevent damage from occurring. At Hague Fasteners, we go the extra mile to protect our components by wax dipping them to prevent knocks and damage after manufacturing. By doing so, we can ensure that our components are received in perfect condition, ready to perform their intended function with reliability and precision.

Hydrogen Embrittlement, Technical Bulletins

Hydrogen Embrittlement

Hydrogen Embrittlement Fasteners

What is Embrittlement

Hydrogen embrittlement is a phenomenon that can occur in fasteners, such as bolts and screws, due to the presence of hydrogen atoms. This process can weaken the structural integrity of the fastener and lead to unexpected failures, which can have serious consequences. In this publication, we will examine the causes and effects of hydrogen embrittlement in fasteners, as well as potential prevention strategies.

Causes

The cause of hydrogen embrittlement in fasteners is the absorption of hydrogen atoms into the metal during manufacturing, processing, or service. Hydrogen can be introduced into the metal through various methods, such as pickling, electroplating, and welding. Once hydrogen atoms are introduced into the metal, they can migrate to areas of high stress concentration, such as the threads or the shank of the fastener. When the hydrogen atoms accumulate in these areas, they can create internal voids or microcracks, which can reduce the ductility and toughness of the metal. As a result, the fastener becomes susceptible to sudden fracture, even under normal loads.

The effect of hydrogen embrittlement in fasteners can be catastrophic, especially in safety-critical applications, such as aerospace, automotive, and construction. The failure of a fastener due to hydrogen embrittlement can lead to equipment malfunction, loss of structural integrity, and even personal injury or loss of life. Moreover, the damage caused by hydrogen embrittlement may not be immediately apparent, as the fastener can fracture without warning after a period of service. This makes it difficult to detect and prevent hydrogen embrittlement in fasteners.

Prevention – Baking

Preventing hydrogen embrittlement in fasteners requires a proactive approach that addresses the sources of hydrogen, the design of the fastener, and the selection of materials and processing methods. One common prevention strategy is to use low-hydrogen processes, such as electroless nickel plating or black oxide coating, that minimize the introduction of hydrogen into the metal. Another approach is to reduce the stress levels in the fastener by using larger diameters, smoother threads, and lower torque values. Additionally, designers can select materials that are less susceptible to hydrogen embrittlement, such as high-strength alloys with low hydrogen affinity.

Heat treatment baking is a common process used to prevent hydrogen embrittlement in high-strength fasteners. This process involves heating the fasteners to a specific temperature for a certain amount of time, which allows any hydrogen that has been absorbed by the metal to diffuse out of the material. The baking process is typically performed after the fasteners have been plated or coated with a hydrogen-absorbing material, such as cadmium or zinc.

During the heat treatment baking process, the fasteners are heated in an oven or furnace to a temperature typically ranging from 375 to 450 degrees Celsius (700 to 840 degrees Fahrenheit) for a period of several hours. The specific temperature and duration of the baking process depend on the type of material being used and the amount of hydrogen that needs to be removed.

The heat treatment baking process can be done using either a batch or continuous process. In a batch process, the fasteners are placed in a rack and then loaded into the oven or furnace, while in a continuous process, the fasteners are conveyed through the oven or furnace on a conveyor belt.

One of the advantages of heat treatment baking is that it is a relatively simple and cost-effective process that can be easily integrated into existing manufacturing processes. It is also a proven method for reducing the risk of hydrogen embrittlement in high-strength fasteners.

However, it is important to note that heat treatment baking is not always effective in preventing hydrogen embrittlement, particularly in cases where the fasteners are exposed to high levels of hydrogen during service. In such cases, alternative methods of preventing hydrogen embrittlement, such as the use of alternative materials or coatings, may be necessary. Overall, heat treatment baking is an important process for ensuring the safety and reliability of high-strength fasteners in a wide range of applications, particularly in industries such as aerospace, automotive, and industrial manufacturing.

Prevention – Materials

To help avoid hydrogen embrittlement, there are several materials and superalloys that are less susceptible to this phenomenon. Here are some examples:

    Austenitic stainless steel: Austenitic stainless steel is a non-magnetic alloy that is resistant to corrosion and hydrogen embrittlement. It contains high levels of nickel and chromium, which provide excellent mechanical properties and resistance to environmental degradation.

    Titanium alloys: Titanium alloys are known for their high strength-to-weight ratio, corrosion resistance, and resistance to hydrogen embrittlement. They are commonly used in aerospace, medical, and industrial applications.

    Inconel alloys: Inconel alloys are a family of nickel-based superalloys that are known for their high temperature strength, corrosion resistance, and resistance to hydrogen embrittlement. They are commonly used in aerospace, marine, and chemical processing applications.

    Monel alloys: Monel alloys are a family of nickel-copper alloys that are highly resistant to corrosion and hydrogen embrittlement. They are commonly used in marine and chemical processing applications.

    Cobalt alloys: Cobalt alloys are a family of high-performance alloys that are known for their high temperature strength, wear resistance, and resistance to hydrogen embrittlement. They are commonly used in aerospace, medical, and industrial applications. It’s important to note that selecting the best material or superalloy for a given application depends on various factors, such as the operating conditions, the type of fastener or component, and the cost. Consulting with a materials engineer or a specialist in the field can help identify the best solution for a particular case.

Conclusion

In conclusion, hydrogen embrittlement in fasteners is a serious issue that can compromise the safety and reliability of equipment and structures. The causes of hydrogen embrittlement are multifaceted and can occur at various stages of the fastener’s life cycle. The effects of hydrogen embrittlement can be catastrophic, leading to sudden failure and potential harm to people and property. Prevention of hydrogen embrittlement requires a holistic approach that includes minimizing the introduction of hydrogen, reducing stress levels, and selecting appropriate materials and processes. By following these best practices, engineers and manufacturers can ensure the integrity and longevity of fasteners in critical applications.

Examples of Failures in Fasteners

  • In 2019, a steel beam collapsed at a construction site in Melbourne, Australia, killing one worker and injuring several others. The cause of the collapse was determined to be the failure of a fastener due to hydrogen embrittlement. The fastener had been recently installed and had not been properly heat-treated, which contributed to its susceptibility to hydrogen embrittlement. (Source: ABC News, “Melbourne worksite collapse: One dead, two critical after scaffolding falls on them,” 23 November 2019)
  • In 2010, a gas pipeline explosion occurred in San Bruno, California, killing eight people and causing significant damage to the surrounding neighborhood. Investigation revealed that the cause of the explosion was a rupture in a pipeline due to hydrogen embrittlement in a weld joint. The fasteners used in the weld joint were found to have absorbed hydrogen during the welding process, which led to their sudden fracture. (Source: National Transportation Safety Board, “Pacific Gas and Electric Company Natural Gas Transmission Pipeline Rupture and Fire,” Accident Report NTSB/PAR-11/01)
  • In 2013, a fire broke out in a Boeing 787 Dreamliner parked at Heathrow Airport in London. Investigation revealed that the cause of the fire was a fractured titanium fastener that held the battery casing in place. The fastener had experienced hydrogen embrittlement, which weakened its structure and led to its sudden failure. (Source: Reuters, “Boeing says Dreamliner fire caused by faulty battery,” 20 March 2014)
  • In 2017, a water tank exploded at a chemical plant in Louisiana, killing three workers and injuring several others. The cause of the explosion was determined to be a failed bolt that had experienced hydrogen embrittlement. The bolt had been recently installed and had not been properly heat-treated, which contributed to its susceptibility to hydrogen embrittlement. (Source: Chemical Safety Board, “CSB releases final report into 2017 fatal incident at the Packaging Corporation of America in DeRidder, Louisiana,” 29 October 2019)
  • In 2017, the U.S. Navy issued a safety bulletin warning of the risk of hydrogen embrittlement in certain types of stainless steel bolts used in shipboard equipment. The bulletin cited several instances of bolt failures due to hydrogen embrittlement, including one incident where a bolt on a high-pressure air compressor failed, causing an explosion and injuries to sailors. (Source: Navy Safety Center, “Hydrogen Embrittlement in Bolts and Screws,” Safety Bulletin 17-01)
  •  In 2019, a bolt failure caused a roller coaster derailment at the Daytona Beach Boardwalk in Florida. The failure was attributed to hydrogen embrittlement, which weakened the bolt and led to its sudden fracture. Two riders were ejected from the coaster and fell 34 feet to the ground, suffering serious injuries. (Source: NBC News, “Roller coaster derailment caused by ‘excessive corrosion’ of support beam, state says,” 17 July 2019)
  • In 2016, the roof of the Allianz Riviera soccer stadium in Nice, France partially collapsed due to the failure of several fasteners. An investigation revealed that the fasteners had experienced hydrogen embrittlement, which weakened their structure and led to their sudden failure. Fortunately, no one was injured in the incident. (Source: The Local France, “Nice stadium roof collapse due to ‘metal fatigue’,” 14 September 2016)
  • In 2018, the roof of the Afsluitdijk road tunnel in the Netherlands partially collapsed, prompting its closure for several months. An investigation revealed that the failure was caused by the corrosion and hydrogen embrittlement of fasteners used to secure the roof panels. The fasteners had been exposed to high levels of saltwater and hydrogen gas, which contributed to their deterioration. (Source: NOS, “Afsluitdijk tunnel closed due to faulty bolts,” 17 January 2018)
  • In 2016, a train derailment occurred in Mosier, Oregon, causing a crude oil spill and fire. Investigation revealed that the cause of the derailment was a broken bolt in the rail joint, which had experienced hydrogen embrittlement. The bolt had been manufactured using a high-strength steel that was susceptible to hydrogen embrittlement, and had been exposed to hydrogen during service. (Source: Federal Railroad Administration, “Railroad Accident Brief: Union Pacific Railroad Derailment,” Accident Report RAB-16-03)

These examples highlight the serious consequences in fasteners, and underscore the importance of taking preventive measures to minimize the risk of failure.

Insulated Bolts, Power Generation, Special Fasteners, Technical Bulletins

Insulated Bolts

Hague Fasteners have been manufacturing High Voltage Insulated Bolts for decades servicing the turbine and power generation maintainers and manufacturers.

Hague’s highest quality British manufactured Turbine Studs and Hex Bolts are wrapped with Epoxy Glass which is then finish machined to make the Insulated Fastener that can then be safely installed within the high voltage generator.

Turbine Rotor Insulated Bolts
Turbine Rotor Insulated Bolts

The bolts pictured are smaller items used in an 11.5kV generator with rotor expiration voltage of 500V.

Turbine Insulated Bolts & Assemblies

Insulating sleeves and washers made in flame retardant epoxy glass are often manufactured to suit the special insulated bolt manufactured typically to OEM designs and drawings.

Insulation Materials

Phenolic Glass B30 – For High temperature Applications

Silicone Glass B32 – For High temperature Applications

Polyimide Glass B34 – High Strength in High Temperature Applications

Epoxy Glass B36 – Superior Grade Laminate

Epoxy Glass B38 (FR) – For Flame Retardant Applications

Epoxy Glass B46 – Improved Machinability Laminate

Epoxy Glass B48 – For Applications At Elevated Temperature Where Good Mechanicals Are Required

Epoxy Glass FR4 Rod – For Flame Retardant Applications

Epoxy Glass G10 – For Commercial Applications

Epoxy Glass G10 QDX – Laminate With Multi-Axis Reinforcement