BS 4870, 4871 & 4872?

"You can't allow him to weld! He's not a qualified welder!" shouted Ring.

"But he has a welder certificate." said Bryan.

"What is going on?" I came to them and wanted to find out why they argued early in the morning.

"Come and see. This welder is certified to BS 4872 part 1 in overhead weld. This job is just a flat position weldment, I don't know why Ring against me."

"I don't intend to argue with you. Do you know what is BS 4872?" Ring was clam down while I joined them.

BS 4872 is "APPROVAL TESTING OF WELDERS WHEN WELDING PROCEDURE APPROVAL IS NOT REQUIRED". Part 1 is Fusion Welding of Steel and Part 2 is TIC & MIG Welding of Aluminium & its alloy. The last est revision is 1982 & 1976 for part 1 & part 2 respectively. It is a very old standard and almost nobody using it to qualify welder now. Normally for each welding job, no matter we are using AWS or BSEN standard, it is necessary to qualify both procedure and welder. However, BS 4872 do not need to have a qualified procedure. It doesn't require any approved procedures to test the skill of welder. BS 4870 is used to qualify procedure and BS 4871 is "APPROVAL TESTING OF WELDERS WORKING TO APPROVED WELDING PROCEDURES".

Now, BS 4871 (part 1 & 2 only)is replaced by BSEN 287 "QUALIFICATION TEST OF WELDERS" and BS 4870 (part 1, 2 & 3) is replaced by BSEN 288 "SPECIFICATION AND APPROVAL OF WELDING PROCEDURES FOR METALLIC MATERIALS". For arc welding of steel, BSEN 288 part 3 "WELDING PROCEDURE TESTS FOR THE ARC WELDING OF STEELS" is superseded by BS EN ISO 15614-1.

"No......but it should be a recognized standard....isn't it?"

"Well, it is a very long story to decribe the change of standards. But I think BS 4872 is not good enough to qualify this welder for this job. Bryan, would you please ask him to test again with the qualify welding procedure? It would be safer for all of us." I said finally.

Add Visitor Counter & Fasterner Tensioning

I've added a visitor counter to my bolg. Although I always think that I am the only one who enter this blog, it is still good to know that if there is someone else here. To write this bolg, I think the main purpose is to drop down some notes to myself. There are so many things in my mind, no matter job related or not, and this is a good time for me to sit down and re-organise the stuffs.

Recently, I am checking some information on bolt tightening. Bolting & Welding are two most popular methods to join machanical parts. As an inspector, some times we need to inspect the condition of bolts. When bolts are tightened, they become stressed in tension. Analysis shows that for a dry (means no lubricant, thread locker, or thread sealant) steel fastener, approximately 50% of the tightening torque applied is needed to overcome friction between nut turning against the joint surface. Another 40% is consumed overcoming friction between the mating threads. The remaining 10% develops useful tension in bolt. This is very interesting. That means if you add some lubrication on the mating threads and joint surface, a same given torque can produce greater preload stress in the fastener. On the other hand, if the joint preparation is not satisfactory and induce more friction, there will be insufficient clamping force on the joint.

Improperly tightened bolts may loosen under vibration, thermal cycles, or other in-service conditions. Such joints can also slip, generating undesirable load paths. It can also cause fastener tension to vary more widely under cyclic loads, leading to early fatigue failure.

What is going on? Still no formal announcement

It has been a tough period for me. There is still no formal annoucement on the organization structure change. My boss is very busy in this period and trying to get as many information as he can. But nobody knows would that be useful if the change is unreal. For me, I have done nothing to prepare for the change. If the change is confirmed, I would stay and wait for the new arrangement. I don't think I am going to accept any unreasonable arrangement.