Span of control

Question: Why do some covered tasks in the ASME B31Q standard list a span of control of 1:0? What does that mean?

Answer: Let me first define span of control. It is the maximum number of nonqualified individuals that a qualified individual can direct and observe performing a covered task. For example, locating underground pipelines is a covered task with a 1:1 span of control. This indicates that a qualified individual can direct, monitor, and observe one unqualified individual in performing all aspects of the pipe locating task.

A span of control 1:0 ratio indicates that the task may not be performed by any unqualified individual (even under the direct observation of a qualified individual). These are a few of the covered tasks: joining pipe by heat fusion, electrofusion, compression fittings, and welding. In other words, the individual performing any of these tasks must be operator qualified.

Tip: Operator qualification (OQ) covered task designations and related issues must be written into the company’s OQ program manual. Span of control ratio requirements may be established in accordance with approved methods described in the ASME B31Q standard (e.g., subject matter expert consensus, rational process to determine task importance).


Surface temperature checks for heater plates

Question: Why do heater plates for fusion require surface temperature checks with a probe when they already have a temperature gauge?

Answer: The dial thermometer on the heater indicates internal temperature which can be different from the actual surface temperature. The dial thermometer can be used as a reference once the surface temperature has been verified with a surface probe (pyrometer).

If the surface temperature is within the proper range, you can then utilize the temperature thermometer on the heater plate, as a reference check prior to inserting the heater plate for each fusion joint. If the reference thermometer temperature drops, the surface temperature should be re-checked. The generator may have run out of gas or a heating element/thermoswitch inside the heater plate may have been damaged (this requires heater repair).

In addition, remember to shield the heater from cold weather and wind by keeping it stored in the insulated sling or stand; when not being used to make a fusion joint.

Tip: Always follow company procedures and/or PE pipe manufacturer’s heating temperature requirements. It is very important that before each fusion joint is made, that the heater surfaces be wiped with a clean, non-synthetic cloth.