Sines, Portugal, Oil, Gas, Chemical, Refinery

Fastening on steel in corrosive environments

Hilti provides a range of faster, more reliable and efficient solutions for fastening to steel

Ideal for corrosive environments, such as the energy and industry sector.

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When you think that your medium-to-large project may need as many as 100,000 fastenings to attach components to structural steel, a faster method for corrosion-resistant fastenings would seem long overdue.

With such volumes, design engineers and contractors working in corrosive environments – like oil & gas, petrochemical, and power & utilities projects – would welcome faster and more efficient ways of fastening components to structural steel. As an additional challenge, the components – such as grating, strut, conduit, cable trays, pipes, electrical boxes, supports for instrumentation panels, etc. – and the fasteners are often exposed to harsh weather, pollution and coastal environments, therefore requiring corrosion protection.

The structural steel may be hot-dip galvanized or coated with paint to help provide adequate corrosion protection depending on the specific environment. However, when fastening components, design engineers and contractors must ensure the corrosion protection of the structural steel is not compromised. The traditional fastening methods used under these conditions include welding, through-bolting and clamping. In this editorial we will compare these with the Hilti methods for fastening on steel and show how Hilti can help save you both time and money.

What is corrosion?

Corrosion is the physicochemical interaction between a metal and its environment, which results in changes in the metal’s properties and may lead to significant functional impairment of the metal, the environment, or the technical system of which they form a part (see ISO 8044:2010).

In construction and engineering corrosion may have a major impact on structures and fastenings made of metals such as carbon steel, stainless steel, zinc, copper and aluminum. It is estimated that roughly one fifth of the world’s annual steel production is to replace parts damaged by corrosion. While this amounts to a considerable economic loss, a greater concern is the safety risks, where corrosion may lead to failure in a fastening system.

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Traditional methods for fastening to steel

Welding

Prepare surface

Time consuming preparation of the coated steel e.g. with an angle grinder
Creates a lot of sparks, which can be a hazard

Weld channel to steel structure

An experienced and certified welder is required
External power supply required, which can be difficult on some jobsites
May require a hot work permit and, on some sites, a dedicated fire watch
Can be weather-dependent

Clean and repaint area

Need to wait until the welded area has cooled down before painting
Multi-layer painting common in the Oil and Gas industry can take 3 to 6 days, including drying time, meaning expensive and time-consuming rework

Through bolting

Multi-step drilling

Drilling process can be time-consuming depending on the thickness and hardness of the steel
Steel exposed from the drilling must be properly coated to avoid corrosion

Secure the channel in place

Access to both sides is needed
Installer needs to work with small parts such as nuts, washers and bolts that may get dropped or lost

Clamping

Position the clamp and channel

Limited in direction of attachment of the component since clamps require a specific orientation relative to the structural steel
Access to both sides of structural steel is needed
Very high material costs, especially for corrosion-resistant clamps in hot-dip galvanized or stainless steel

Complete the fastening

Proper tightening is necessary, however over-torqueing may cause damage to the coating of the steel
If clamp is exposed to vibration then periodic maintenance might be required

Innovative Hilti methods for fastening to steel

Hilti offers a variety of methods customized to various corrosive environments that help reduce or eliminate the drawbacks of traditional methods. Depending on the corrosive environment and type and thickness of the base material, Hilti offers three different fastening options. These solutions help maintain the corrosion resistance of the structural steel and the connection to the non-structural components.

Three fast and reliable ways for fastening to steel

Sharp tip fastening

A fastening technology where a sharp tip stainless steel fastener is driven by a powder-actuated tool into the base material, creating a high-quality connection.

Suitable for high-frequency fastening where the fastening can be completed in a few seconds

Stainless steel fasteners for mildly-corrosive environments where penetration through base steel is acceptable.

Watch the sharp tip video

Diagram of a cross-section of steel showing blunt tip fastening

X-BT blunt tip fastening

A revolutionary fastening technology where a blunt-tip stainless steel fastener with a smooth cylindrical or conical shank is driven by a powder-actuated tool into a pre-drilled hole in the base material, creating a high-quality connection.

No damage to the corrosion protection coating in non-through penetration applications
Fastenings in less than 2 minutes

Duplex stainless steel fasteners for highly-corrosive environments. Fiber reinforced polymer (FRP) / duplex stainless steel fasteners for mildly-corrosive environments.

Watch the blunt tip video BX 3-BT fastening tool for X-BT threaded stud

Diagram of a cross-section of steel showing blunt tip screw fastening

S-BT blunt tip screw fastening

A revolutionary fastening technology where a blunt-tip stainless steel fastener with a screw type shank is driven by a torque controlled screw driver into the pre-drilled hole in the base material creating a tapped connection.

No damage to the corrosion protection coating in non-through penetration applications
Fastenings in less than 2 minutes

Duplex stainless steel fasteners for highly-corrosive environments. Duplex coated carbon steel fasteners for mildly-corrosive environments.

Watch the blunt tip screw video

Advantages over traditional methods

Preparing the coated steel using an angle grinder — Eliminates the need for base material preparation and re-work

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Eliminates the need for base material preparation and re-work

Unlike welding or through bolting, Hilti fastening solutions do not require preparation of base material and re-work after the fastening is made. This makes the overall installation much faster, while providing reliable corrosion protection.

Welding channel to the steel structure — Skilled welder is not required

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Skilled welder is not required

Hilti blunt tip fastening on steel can be completed by any trained operator and do not require a certified welder. Therefore, contractors can deploy welders to other critical applications where welding is an absolute must.

Clamping requires access to both sides of the steel — Only access to one side of the steel is needed

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Only access to one side of the steel is needed

Unlike through bolting or clamping, Hilti fastening solutions do not require access to both sides of the steel. This further improves operator safety as there is no need to get fingers into tight spaces.

Fastening made using a Hilti powder-actuated nailer — Weather independent and no external power source required

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Weather independent and no external power source required

Hilti sharp tip solutions are for powder-actuated nailers, so can be used under all weather conditions. Cordless drills used for blunt tip solutions are built for tough jobsite conditions, so can be used in nearly all weathers. In addition, the cordless tools are powered by 22V Li-ion batteries so do not require a mains power supply.

Logos of the industry approvals Hilti has been awarded for fastening to steel — Backed by testing and approval

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Backed by testing and approval

Hilti provides comprehensive technical data for different thicknesses and strengths of base steel. This data is backed by International Codes Council’s Evaluation Service (ICC-ES) as well as industry approvals including, but not limited to, the American Bureau of Shipping (ABS). In addition, Hilti blunt tip screw fastening technology has been tested, and is approved for use, in aluminum base material.

Fastening being checked for the correct embedment using a check gauge — Easy to check installation quality

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Easy to check installation quality

Both Hilti sharp tip and blunt tip fasteners are easy to inspect after installation using a visual check or a check gauge.

Cross section showing that blunt tip fastening does not penetrate through the steel — No through penetration or damage to the back of the steel

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No through penetration or damage to the back of the steel

With Hilti blunt tip technology, fastenings can be completed without damaging the corrosion protection coating, making it ideal for highly-corrosive environments.

Which technology is right for me?

Sharp tip fastening

Base material
Steel

Minimum thickness
6 mm

Through penetration
Yes

Tool required
DX 5 or DX 450 or DX 460

Available thread diameter
M8

Fastener material
SS A2 equivalent

X-BT blunt tip fastening

Base material
Steel, stainless steel, cast iron

Minimum thichness
8 mm

Through penetration
No

Tool required
SF BT A22 and DX 351-BT(G)

Available thread diameter
M6, W6, M8, M10, W10

Fastener material
SS A4 equivalent and FRP (X-BT-MF)

S-BT blunt tip screw fastening

Base material
Steel, aluminum

Minimum thichness
6 mm

Minimum thichness
No

Tool required
SBT 4-A22

Available thread diameter
M8, M10, W10

Fastener material
SS A4 equivalent and duplex coated carbon steel

Key applications

Electrical Connections

Fasteners for earthing, bonding and lightning protection.

More information

Fixing gratings and checker plates

A wide range of corrosion and vibration resistant fastening solutions – without the need for clamping, welding and through bolting.

More information

Fixing electrical elements to steel with Hilti direct fastening tools

Fastening modular support and electrical elements to steel

Fasten electrical boxes, panels, brackets, cable trays, cable ladders and other electrical elements to steel. Our fasteners are also compatible with Hilti modular support systems.

More information

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