HEICO Fastening Systems

The HEICO-TEC® Mechanical Bolt Tensioning System

Large bolted joints are found throughout the Iron, Steel, Forging and supporting industries: large diameter tie rods, press columns, foundation bolts, cranes, material handling attachments, pumps and compressors among others.  Correctly tightening bolts greater than one inch in diameter becomes a challenge that often requires large, cumbersome and expensive hydraulic or pneumatic torque or tensioning tools.

Since the advent of the mechanical tensioner, many applications and processes have benefited for both the technician in the field, on the mill floor and with the OEM design engineer.  The HEICO Group’s design engineering team has taken this technology and incorporated multiple notable improvements.  The HEICO-TEC® family of tensioning products provides the market with a fast, safe, precise and reusable method to tighten the largest of bolted joints. 

The HEICO-TEC® Tensioning System’s performance has been independently verified by DNV to meet global standards of tightening accuracy, reuse and strength class proof loads.  The HEICO-TEC® is designed to be compatible with heavy hex nuts and bolts used in existing applications as a one-for-one replacement.

The HEICO-TEC® design prevents damage to the primary bolt threads since only tension is exerted on the bolt.  The two part pressure bolt/pin is designed to prevent harmful torsion stresses, bending and other damage that could severely impact field performance and reuse.  Additionally, friction conditions are secured and stable since HEICO-TEC® lubrication is enclosed and protected within the pressure bolt bore, preventing exposure to the outside environment.   All HEICO-TEC® tensioners leave our factory pre-lubricated ready to install on the application with no additional preparation required.

Although power tools can be used to tighten the HEICO-TEC® mechanical tensioner, accurate tensioning can also be achieved by a common torque wrench and appropriate sized socket- two items that are generally on hand in even the most remote field site.  This is a huge benefit when clearance issues arise that would prevent easy access by a power tool.  With a torque wrench, an operator can easily access tight spaces in order to tighten or loosen the HEICO-TEC® tensioner.

The standard HEICO-TEC® tension nut is heavily stocked in Hickory, NC in both inch and metric sizes, in strength grades B, C, DH (ASTM A354) and classes 8 and 10 (ISO 898-2).  Additionally, HEICO-TEC® Tension Nuts are available in both uncoated and zinc-flake coated material.  Custom HEICO-TEC® tensioners can also be custom designed, specific to an application’s unique requirements, such as size, materials, strength and non-standard thread types/pitches.

In summary, the advantages of HEICO-TEC® mechanical tensioners over other large bolt tensioning methods are:

• Simple- hand-held torque wrench is all that is needed to tighten or loosen.  Hydraulic and pneumatic tools can also be used.
• Fast- no need for long times associated with transport and setup (pumps, hoses, calibration) of other tensioning methods.
• Reliable- due to the elastic, spring-like pressure pin, elasticity of the bolted joint increases which compensates for settlement and preserves preload.
• Safe- highly resistant to bolted joint self-loosening, since the design performs as if it has a greater clamping length.  Also, no hydraulics or heat required increasing installation safety factor. 
• Durable- contributes to the increased service life of the bolted joint, due to the elasticity provided.
• Precise- controlled friction characteristics ensures tightening and reuse accuracy- confirmed by stringent DNV testing.
• Reusable- no damage occurs with tightening/loosening procedure, so reuse is assured.  No damage to the threads of the bolt or threaded rod, since tightening is executed with pure tension and not torque.
• Compatible- one for one replacement of any heavy hex nut; complies with ISO 898-2 and ASTM A354 requirements. 
• Economical- saves on installation costs and lifetime resilience of the assembly.

HEICO-LOCK® Wedge Locking Systems

HEICO-LOCK® Wedge Lock Washers

Self-loosening of critical bolted joints can result in extremely negative situations: machine damage, loss of revenue, work stoppages and even harm to personnel.  HEICO-LOCK^® wedge locking systems prevent bolt loosening through tension principles and not with commonly used friction-based locking methods or chemical adhesives.  

This is a two-part lock washer consisting of identical pairs with radial teeth/serrated edges on the outside and wedged surfaces on the insides.  When the bolt is tightened, the external radial teeth of the HEICO-LOCK^® wedge lock washers imprint into the mating surfaces while simultaneously engaging the interlocking internal wedges. 

If the bolted joint is subject to dynamic stresses (vibration, dynamic loads), movement is only possible between the wedge lock washer’s internal wedge-shaped surfaces, which creates a slight increase in the clamping forces. Since the wedge angle is greater than the angle of the bolt’s pitch thread, self-loosening potential is eliminated.

Characteristics:

• Certified and proven (DIN 25201-4, DIN 65151, NASM 1312-7)
• Performance ensured whether lubrication is/is not used
• Can be reused
• Easy to install; comes as a pre-assembled pair
• Suitable for up to 12.9 strength class and grade 8 bolts and their respective nuts
• Available in zinc-flake coated carbon steel, stainless steel, SMO 254 and Inconel 718, in both narrow and enlarged OD’s
• Heavily stocked in Hickory, NC in standard sizes up to 3” and M76
• Custom sizes and coatings available

HEICO Fastening System’s family of wedge locking washers are a proven critical bolt locking method used throughout heavy industry.  HEICO-LOCK^® wedge lock washers are the ultimate insurance to prevent self-loosening of a bolted joint under intense vibration and dynamic loads.

HEICO-LOCK® Combi-Washers

The Combi-Washer is HEICO’s newest addition to the proven wedge lock washer family of clamp-load securing lock washers.  The Combi-Washer offers huge advantages to the Distributor, OEM and End User in improving existing applications and granting safety and performance measures to new designs. 

How is the Combi-Washer different from the standard HEICO-LOCK® wedge lock washer?  A thermoplastic inner ring secures the two wedge lock washer halves into one unit and tabs on the inner locking ring provide a semi-fixed connection to any same sized bolt, creating a SEMS-like bolt assembly.  Advantages Include:

• Identical performance to the standard HEICO-LOCK® wedge lock washer
• Easily mounted to all commercially available bolts
• Ensures correct orientation of washer halves after initial installation (no adhesive)
• Increased cost value due to efficiencies in time and streamlining
• Advantageous to both kitting scenarios, serial production and MRO applications
• Available in metric sizes from M8-M16 and inch sizes from 3/8”-3/4”.  Other sizes available on demand.  Available in both standard and enlarged OD.

HEICO-LOCK® Wedge Lock Nuts

HEICO's Wedge Lock Nuts permanently combine the HEICO-LOCK® wedge lock washer with a right sized nut to create a single unit, quickening assembly times and preventing incorrect joint assembly.  When properly torqued, the geometry of the wedge lock washer ensures the bolted joint will not self-loosen under the most extreme conditions of high vibration, shock/dynamic loading and high thermal variations.  Available in common inch & metric sizes, in both course and fine threads.    

If you need a simple, fast and reliable solution to keeping bolted joints tight, or just want to know more about our other critical bolted joint solutions, please visit us at AISTech Booth 2365.  You can also contact HEICO Fastening Systems at phone 888.822.5661, email sales@heico-lock.us or go to https://www.heico-lock.us.