Holt Brothers Limited (Halifax) 24601 – Vertical split furnace
Case Study
Commissioned December 2015
Almor secured an order in from Holt Brothers Limited (HBL) based in Halifax for heat treatment
equipment comprising of a 5 metre high vertical split furnace that was designed and built by Almor.
HBL are specialist in the heat treatment industry for large shafts for use in the North Sea oil and gas
rigs. HBL needed to procure a new heat treatment plant for a customer who specifically needs to heat
treat shafts up to 5 metres in length but in the vertical position. It is common practice in the industry to
heat treat these shafts in the horizontal position as it is easier to heat treat this way but the customer
standard required a vertical orientation.
The new equipment had to be engineered with the top section made as a clamp shell (two doors that
open) and the bottom section as a solid circular construction with a re-circulating fan. The reason for
this type of construction is for ease of product loading due to factory space limitations and for rapid
cooling.
The customer needed a very fast temperature cool down rate to assist with the process but also to
improve production time. The lid is removed from the top of the furnace at maximum temperature and
the doors open below 200 deg C. The furnace uses low thermal mass insulation and for example will
heat a 500kg load to 550 deg C, dwell at temperature for one hour and cool to ambient in a total of 4.5
hours.
The furnace meets AMS 2750E class 3 and has instrumentation type B. The maximum temperature
is rates at 6250C with a working volume of 5000mm high x 800mm diameter. Air re-circulation with a
fan in the base and two zone control.
The product is suspended from a support frame mounted at the top of the chamber and the lid lifts off
for rapid cooling. The support frame is expected to deflect (sag) with time and therefore a special
design was adopted that enabled the support frame to be turned upside down and be used in two
orientations
Photographs
3D CAD drawing of the furnace positioned in the pit at the customer site
3D CAD generated front view of complete furnace (doors open)
Front photograph of furnace
3D CAD drawing superimposed onto a site photograph showing the support frame (in blue)
3D CAD drawing showing the doors open, support frame and base with the fan assembly and lid
removed for clarity.