VOLUME 28 NO. 2

Over the past year, Gem Equipment has made a strong effort to upgrade piping used in frying systems.  This effort has resulted in changes in material specified, welding procedures and quality control.  While it will take several years to determine total effectiveness, these changes will reduce the number of leaks encountered as the new fryer piping ages.  Most of the fryers manufactured by this company are sold to french fry potato processors.  Kettles, piping and most other oil contact parts are made of carbon steel.  Harsh chemicals are used to clean these systems.  As long as proper clean-up procedures are used and there is no area that holds the chemicals after a fresh water wash, little if any damage is caused by the chemicals.  Any fissure, crack or dam inside the piping that keeps  chemicals from totally draining out of the piping, will cause leaks at sometime during the life of the fryer.

Surprising as it may seem, careful inspection of commodity grade welded steel pipe discovered sections that did not have full penetration in the seam welded by the pipe manufacturer.  Some samples had a fissure inside the pipe, caused by lack of weld penetration that were as bad as any found in the worst field welds.  This problem was relatively easy to overcome.  Gem Equipment is now specifying seamless pipe for all carbon steel fryer piping systems.  Welding changes were more comprehensive.   One outside source suggested x-ray quality welds.  This suggestion was rejected.  One criteria for an x-ray quality welds is zero porosity.  Another is that the weld be at least as thick as the parent material.  In practice for pipe a weld, the weld will extend as much as ¼ inch inside the pipe.  This means that an x-ray quality weld in a horizontal run of pipe would form a ¼ inch dam in the bottom of the pipe.  Ideally, the inside surface of a weld at the bottom of a horizontal run of pipe, should be at exactly the same elevation as the bottom of the pipe.  Until recently, it was difficult to inspect pipe welds from the inside.

New tools for quality control have come to the rescue.  Devices are now being used that provide for inspecting welds inside piping up to 20 feet from the nearest opening.  A probe is inserted in the pipe until the sensor reaches the weld.  A photographic image of the weld is transmitted to a screen, which stays outside the pipe.  This inspection device works readily on pipe as small a 1-1/2 inches, and with a mirror will work even on smaller pipe.  All welds on fryer piping over 1 inch in diameter are now being inspected from inside.  A materials testing lab recommended the use of corrosion resistant filler wire for the root pass on carbon steel pipe welds.  Carbon steel wire is used for the outside weld passes.  Gem Equipment is now using these standards for welding carbon steel fryer piping.  The same inspection and welding standards are also being used for carbon steel fryer oil return ducts.  The manufacturer of the probe described above has added one more feature.  Gem just purchased a unit that extends the same 20 feet inside the pipe and records images on a digital photo card.  This allows images of welds inside pipes to be handled just like any other digital photograph.  They can be viewed on a computer monitor, E-mailed or printed.