Skip to main content

Hollo Bolt: How does it work?

In hollow rectangular solid material (RHS) construction, the hollo bolt (TM) was developed to fasten materials such as steel I-beams to this hollow but strong material. Hollo bolt fasteners are used around the world in the construction of multi-story buildings, bridges, highway overpasses and various other applications where solid metal hollows are fastened together. Find out more about how the hollo bolt works below.

hollo bolt usage

Flow drilling

Flow drilling is the process of drilling a hole through hollow structural materials, such as rectangular steel pipes, without actually removing any of the metal. The hole is automatically sealed around its edge as it is formed. A tool called a threaded roll then draws a thread on the circumference of the hole, allowing it to accept a standard threaded bolt as a fastener.

The Hollo Bolt

The Hollo-Bolt assembly has 3 parts, the cone, the body and also the threaded bolt. It is pre-assembled and comes in a wide range of sizes for various clamping requirements. The Hollo Bolt is created of mild steel, with a zinc coating to stop corrosion. Custom made Hollo bolts can be manufactured from high quality stainless steel. The Hollo Bolt can also be manufactured with a socket or button head, or with a countersunk set screw. Hollo bolts are manufactured in a variety of strengths to provide greater structural integrity than other types of fasteners. Contact Lindapter for more info.

Hollo Bolt Sizes

Hollo bolts are produced in sizes from 4 1/2 cm (1 3/4 inches) to eight cm (3 1/4 inches) long.

Advantages of Hollo screws

Due to the consistency of Hollo Bolts, a typical size may be chosen and used throughout the development project, saving time and inventory costs. Hollo Bolt fasteners also minimize the amount of welds that must be accustomed join metal to metal, reducing costs and increasing worker safety.

Hollo bolt insertion

The Hollo Bolt inserts into drilled flow holes in both the structural material and the element to be fastened, up to the bolt collar. The hex head of the bolt protrudes past the collar. Hollo bolts can be inserted at any angle of the material from 30 to 90 degrees.

hollo-bolt lindapter

Tighten the Hollo bolt

The Hollo Bolt is tightened by placing an open end wrench around the collar to hold it steady and placing an appropriately sized torque wrench on the hex head to tighten it. An electric key is being developed that can perform both functions at the same time. By applying torque to the hex head, the flanges on the body of the Hollo Bolt open, anchoring the fastener deep into the solid structural hollow material.

Hollo bolt sealing

Various sealants have been developed for Hollo Bolt to reduce water penetration. Information on these is available from the manufacturer, Lindapter.

How many Hollo screws to use?

At least 4 Hollo bolts must be used to fasten a plate to a solid structural hole. Typically, 8 Hollo Bolts are used, in a 2 column format, depending on the width of the plate. Measure carefully when placing the Hollo bolts through the adjacent faces of the structural hollow solid in order that the bolts don't acquire contact with one another.

lindapter hollo-bolt

Procedure to remove a pre-installed Hollo-Bolt

Using a pneumatic tool to remove the Hollo-Bolts:

  1. Put pneumatic hand tool in reverse mode - counterclockwise rotation.
  2. Place an appropriately sized wrench (depending on the size of the necklace) on the flats of the necklace to hold it in place.
  3. Use the pneumatic tool to loosen the bolt.
  4. Continue in reverse mode until the cone inside of the RHS at the opposite end of the bolt is released to drop into the RHS.
  5. The bolt can now be removed as can the sleeve by prying off the collar with a pinch or pry.


Popular posts from this blog

Metal roof restoration

What does metal roof restoration consist of? When a ceiling is very deteriorated and has lost its luminosity, aesthetics and hygiene properties, a cleaning, no matter how deep, is not enough to get the ceiling of your company to be like new and therefore it is required a specific treatment that recovers it.  During metal roof restoration, suitable resins for this type of ceiling are micro-sprayed that aesthetically equalize the false ceiling and eliminate all the grease, carbon monoxide, nicotines, bacteria and fungi that may have adhered to the ceiling.  The  result is spectacular  and the client is  as if he were re-releasing his roof but for a much lower price than  the one that would mean replacing all the metal plates.  A company may need metal roof restoration both if it has not carried out professional ceiling cleaning for years or if cleaning has been carried out but in an inadequate way, since to preserve the characteristics of the metal roof it is necessary to use produc


Hydraulic faults are a common occurrence in most homes. Although many times it is possible to try to deal with the problem ourselves, the truth is that only a professional plumber can repair the damage. What makes a professional plumber necessary is how unexpectedly hydraulic failures occur and how quickly the problem escalates. It is a fact that without the necessary technical knowledge, it is quite possible to make things worse and in the end pay a fortune to repair the damage.Plumbing is a complex system that needs special treatment. One wrong move can lead to a catastrophic flood in your home. They cause water to overflow or stagnate and are one of the most common causes of hydraulic failure.Leaking from the toilet or sewer is a common occurrence They are often the cause of mold and moisture. They can be replaced or repaired only with the help of a specialized plumber.They can be the cause of the lack of hot water but also for another series of problems in the plumbing of your spa

Business accounts yourself is easy, I thought.

I used to think that really: bookkeeping is easy. You enter an amount on the left, an equal amount on the right and if the amounts at the bottom of the line are the same, everything is okay. This thought remained until I started working with an Business accounts package. Different booking rules had to be created per event. And for some reason, accounting packages are ready to support any multinational, but it is far too complex for an average self-employed person. Curious as I am, I started researching why accounting is so difficult. The reason was quickly found. Traditional accounting, or the 'double accounting method', dates from the 15th century. Conceived by the Italian monk Luca Pacioli. In those days, bookkeeping was still a quill pen. Then it was useful to work with diaries, journal entries and ledgers. With the double accounting method you can spot errors and check the books afterwards. A nice system for that time. With the introduction of the computer, the unfortunate