Page 39 - Gi_March2020

igem news – yppc

FIGURE 1 EXAMPLE BS746 ADAPTOR AND METER UNION FIGURE 2 PROTOTYPE SPANNER SET AND INDIVIDUAL SPANNER

FIGURE 3 PRODUCTION SET – COMPONENTS AND BOXED SET

The problem
The issue I first encountered (and
saw repeatedly when exchanging gas
meters) was overtightening by the
original installer.
Elastomeric washers were brittle
and over-compressed on removal.
On inspection of the connection on
the meter itself, washer seats were
often seen to have a layer of thin rust,
indicating that moisture had worked
into the connection. The likely cause
of the corrosion was overtightening of
the nut on the meter union, causing seized and the meter connection Once the problems had been identified,
excessive compression of the washer. broke off from the meter casing. The I initially had the idea of creating seven
The washer becomes hardened over installation had to be cut out and double open-ended spanners, with lugs
time and can no longer accommodate completely re-piped as a result. to attach a bar for extra leverage.
expansion and contraction of the joint Another issue with pipe wrenches and I hunted for a manufacturer who
with temperature changes, thus leading similar tools is they are often toothed, would be willing to help me develop the
to leakage and moisture ingress. Most and cause damage to the brass fittings. design. Maun Industries was interested
of the time, the leakage is minimal and These can become sharp or rounded off, and could see the benefit of the
usually detected by the end user. presenting a cut hazard and the risk of innovation to the industry, so we worked
However, this situation still causes slipping when applying force. on a set of prototypes to be field-tested
unnecessary calls to the gas emergency Pipe wrenches in the wrong by EMS and our subcontractors.
line, load on the network staff to attend application have been the cause The decision was taken in the interest
and make safe, usually some time off gas of many a bruised knuckle, as any of saving material and weight to separate
for the customer and an attendance by pipefitter will confirm. The larger all the spanner jaws and use a single
the meter operator to make the repair. diameters also require a jaw opening drive bar. The drive would be via ½in
All of this could be avoided by up to 86mm, which tends to only be square drive on a breaker bar, with an
correctly tightening the connection available on large, long tools with eight-pointed star cut-out to allow fitting
at the time of installation. One of the handles in excess of 600mm. of the drive bar in eight positions.
most extreme cases of overtightening These also tend to be weighty, adding Also, in the set is an octagonal key
I observed was on an old U40 meter to the overtightening problem due to for use inside the adaptor fitting, from
installation in a brick house in a the lever length. To compound all of 2in BSPM to 2in BS746M, which has
churchyard, which had become the above, the meter itself is quite often an internal hexagon profile for fitting.
excessively corroded. The meter boxed in or hard to fully access, and once The spanners were to be made of 6mm
unions were so tight and corroded overtightened can make life extremely waterjet cut steel, then case hardened
that when I took a pipe wrench to difficult for engineers in the future. and laser etched.
the fitting, the union was completely Initial design and manufacture

39

13/02/2020 13:28
IGEMNews_YPPC.indd 2
IGEMNews_YPPC.indd 2 13/02/2020 13:28