Are Joint Pins Safe for All Scaffolding Types? Seeking Advice on Steel Tubular Use

Dear All, Joint pins are used in scaffolding to connect two vertical pipes. I would like to know whether this practice is common for all types of scaffolds.

Cuplock Scaffolding

In Cuplock Scaffolding, we are using joint pins.

Steel Tubular Scaffolding

In Steel Tubular Scaffolding, are joint pins advisable to use or not? If we recommend the following in the case of steel tubular scaffolding instead of joint pins, are there any issues? "If two pipes are connected, are they overlapped at least 600 mm and at least two clamps used?"

Please come forward with your views.

Dear Dipil, No, Mr. Dipil, we can't use joint pins on cup lock scaffolding without manufacturer advice. Modifying anything without proper guidance can lead to accidents, and this doesn't apply only to scaffolding but to all equipment and machinery. Hope I am right!!!

Team,

Please come forward, share your expertise with us, and advise me if I am wrong! Keep on sharing.

Regards

Scaffolding Specialization and Joint Types

I remember having some discussion on scaffolding earlier. I reiterate that scaffolding is a specialization. A well-trained scaffolding supervisor/inspector should be on-site to oversee scaffolding work. However, your questions are answered here with an attachment.

A "brace joint" and a "runner/transom joint" are also provided for your information. I hope this will answer your question.

Regards,
Kesava Pillai

Dear Sir, thanks for your reply. It almost clears my query. We had a very good discussion on scaffolding in this forum, which was also very helpful. I request you to go through the attachment and help me in clearing the following doubts regarding Joint Pins. The attachment shows the current practice we are following in our plant for making scaffolding.

Questions Regarding Joint Pins

1. Is what is shown in the picture the right practice?

2. Should we demand the use of Joint Pins instead of overlapping for connecting pipes vertically? What are the issues with such overlapping?

3. When using Joint Pins, if the verticality of scaffolding is not maintained at the plumb level, could tension load come on the joint pin, potentially causing scaffold collapse? Please explain.

4. Please let me know the specifications for buying Joint Pins.

@All: Please do have a look at the attachment and let me know your valuable inputs.

Regards

Maybe the following attachments from my archives could help.

Dear Dipil,

Principle of Scaffolding

The first principle in scaffolding is that the scaffold must be plumb and level in every respect. This principle is applicable to every component, be it a standard, a ledger, or a transom. That is why every scaffold craftsman carries a spirit level in his pouch at all times.

What I have seen in your pictures is the worst-case scenario I have ever come across. It is a horrible mistake. I am sure you do not have a trained scaffold crew at your site. If you have regular scaffolding work, it is high time that you train your crew to prevent any mishaps. (Scaffold work is a specialization, I repeat.)

You can join pipes using double couplers for bracing and bearer/ledger. Even then, there is a specific calculation for spacing the couplers, which you can refer to from the figures I have provided.

Standards and Couplers

For standards, you have to use joint pins or "sleeve coupler," also known as "end-to-end sleeve coupler." Overlapping and joining standards is not permitted as the scaffold will never be plumb with it. A sleeve coupler sketch is also attached for you to review.

Your specification should be "Pressed Steel Joint Pin Coupler, European Quality Standard EN74 or BS 1139, tested to ensure quality standards are maintained. Preferably zinc-plated for longer life. Length 225 to 235 mm for 48.3mm O/D Tube (or specify tube size).

End-to-end sleeve coupler Carbon steel, Diameter: 48.3mm as per EN74/BS1139."

Regards,
Kesava Pillai

Sleeve Coupler Sketch

The sleeve coupler sketch is attached.

Regards,
Kesava Pillai

Dear Sir, thanks a lot for providing such detailed information regarding joint pins. Actually, we have a corporate standard for making scaffolding, which mentions the use of joint pins, but it lacks supportive documents. As we have different standards, we have different act groups consisting of Line Engineers/Managers to implement these standards. The Act Group leader, who was trained on this standard, mentioned that the joint pin specified in the corporate standard is only applicable to system scaffolds (cup lock scaffolding) and not to tube and coupler scaffolds (steel tubular scaffolding). I didn't have any technical details to convince him about the requirement of joint pins in tube and coupler scaffolds, hence I started this thread.

With the details you provided, I have sent him an email with a copy to my boss, advising him to procure the joint pins at the earliest. Once I receive feedback from my management on this issue, I will let you know the status. Thanks once again. This information is certainly helpful at the right time, and I hope if I succeed in implementing this practice in our plant, it will be a great initiative.

Today, I spoke to two people, the main foreman and supervisor of our scaffolding contractor. Both have more than 15 years of experience in making scaffolding. They have worked on more than 20-25 sites in India. Except for one refinery, they have been making scaffolding using the overlapping method everywhere. However, they are ready to build with joint pins and say it's good as well.

Thank you, sir, for providing such technical explanations. I look forward to your help in the future too.

Regards.

Dear Kesava,

As I understand, a sleeve coupler should be used for joining horizontal pipes, i.e., ledger, and not standard, as these couplers are not designed for compression load. The design of the sleeve coupler should overlap more with two pins on one member.

Dear DILIP,

While using joint pin joints, they should stagger and not come in the same plane.