OMS clients have come to expect tools and services which can be traced back to National Standards as part of the service. Without this level of traceability, measurements can be rendered worthless for meaningful or important application purposes. Ultimately, all measurements should sufficiently traceable that the data or information will pass any test of accuracy.
So how can we do this for the humble square?
The ‘square’ is a device used by professionals across countless industries. From carpenters to engineers, this essential tool is the mainstay of many a toolkit. You would imagine that such a tried, tested and simple device would obviously be fit for purpose, right?
It is well worth asking the question - is the square that you have been using, relying on and trusting, truly square? Well, thankfully, the answer to that question is quite easy to establish if you have a surface with a straight edge. Firstly, position the square on the surface and mark a line. Then turn the square over so the stock (the part that is pushed against the edge) is facing the opposite direction. Line this up with the line that you drew, close to the stock and put another line on the surface. If these two lines are not coincident with each other but form a sort of ‘V’ shape, then you can deduce that the extent to which these two lines mismatch with each other is twice the out-of-squareness the tool.
Figure 1: check the square by marking two lines
However, whilst you may have established that there is either (A) a problem with a square or (B) the square appears to be fit for purpose, you will note that none of this is quantified. The absence of any metric and traceable knowledge regarding the square is a fundamental problem for any work where there might be consequences to getting something wrong.
I have had the opportunity to visit many pipe mills over the years, and have worked in a few of them too. I have often asked to be shown the tools that are used to measure end squareness. On one occasion, in a pipe mill that manufactured extremely high-value pipes, I was shown the device that they were using. It has been purchased from a local hardware store and was probably sufficient for woodwork but not for signing off on a valuable pipe costing many thousands of dollars. Seeing this prompted me to question how such methods can be used and relied upon, and the potential for blunders occurring as a result of poor measurement. The main reason could be a lack of consequences for getting this measurement wrong, general complacency or just ignorance about how this measurement could be performed with greater accuracy.
When OMS had the opportunity to put our expertise to the test for a client in a highly significant pipeline crossing many states in the US, we developed our first traceable square. For the first time, we were able to show a path to traceability and also to obtain direct measurements of the out-of-squareness of a pipe.
The method we used was to create our own engineering square and to incorporate a calibrated dial gauge in the design. The resulting tool is being used in the following figure.
Figure 2: field operation of the first OMS digital square
The stock was moved along the pipe wall until the bottom of the square came in contact with the pipe. The end of the pipe closest to the stock was then measured using a dial gauge. The calibration sticker of which can be seen to the left of the image. The tool itself was calibrated by ‘zeroing’ the dial gauge with the square placed in contact with a calibrated square, for which there was a calibration certificate and full traceability.
Figure 3: square being set up with a verification square prior to use
This set-up square was too heavy to be used in practice but provided the essential traceability and verification checks on a regular basis.
In response to demand from OMS clients, we provide squares for sale. We have also undertaken a design performance and usability review and discovered that we could make a further, quite significant improvements to the device. A potential weakness of the initial design was that operator could put pressure on the square by attempting to move the stock. On the redesigned system, the dial gauge has been moved to the opposite end of the blade, thus only ever exerting the same force on the blade and providing more repeatable results with less operator bias.
Other beneficial features include the use of carbon fibre tubes to ensure that the device is light and portable, and also the ability to change the position of the contact points in order to measure differing size pipes or objects.
Figure 4: current design of the OMS digital square
Further advances to the tool offer Bluetooth operation, allowing the operator to log results automatically to a tablet, making this not only a unique square in that it is traceable, but also one that reduces operator transcription errors because it is fully digital.
To find out more about improving squareness measurement, or to purchase one of our tools, contact +44(0) 1279 656038, or email firstname.lastname@example.org.