Observation

Most of the candidates were able to:

• List the three types of pipes used in plumbing and pipe fitting;
• List types of oxyacetylene welded flames.

However, few candidates were unable to explain the following methods of jointing steel pipes.
-           screwed joint;
-           flanged joint;
-           autogenous  welded joint.

The expected response to question 2 is as given below:

(a)   TYPES OF PIPES USED IN PLUMBING AND PIPE FITTING:

• Cast iron pipes;
• Copper pipes;
• Mild steel pipes;
• Stainless steel pipes;
• UPVC pipes;
• PVC pipes.

(b)   METHODS OF JOINTING STEEL PIPES:
        (i)  Screwed joint is used for small or large diameter pipes. It involves theuseof screw fittings to connect or join pipes together. Fittings used  includetee,elbows, nipples, etc.
        (ii) Flanged joint is an excellent method of jointing large diameter pipes through the use of flanges. The flanges may be of cast iron or steel, which are screwed to ends of the pipes. A high quality rubber is usually inserted in between the two flanges for watertighteness.
        (iii) Autogenouswelded joint is welding of pipes using filler rods, made of same material as the pipe. The joint is reinforced by building up beads on the outside of the pipe.         
(c)   TYPES OF OXYACETYLENE WELDING FLAMES:

• Carburizing flame;
• Neutral flame;
• Oxidizing flame