Valve Covers and their Construction
Valve covers have a number alternate names -
Municipal boxes, Inspection covers, Fitzroy box, Stop tap box, Inspection box,
municipal water meter boxes
Note as this an Australian website - footpaths will be used for side-walks.
Valve covers are rather like icebergs. Most of the structure is unseen below the
ground / roadway. See image from DASPYL ... Only the top with lugs could be
seen on footpaths.
There are two sections - the casing and the cover (or top).
The casing is the surrounding structure that protects the stop valves within.
In the past the construction material has been steel and with more modern developments - ductile iron. The latter is a very strong and sturdy form of cast
iron. Extremely suitable for high impact areas such as roadways. Sometimes the casing is a simple affair (such as old square covers) wthere there is four walls and
no base. Others have far more structure - particularly those for roadways where its
needed for stability. Thus small casings on footpaths (with far less wear) would
have smaller below ground structure.
The cover is the top part which is removable. Access can be by hinge (Either visible or hidden. Common with square covers.), a simple locking thread (square/round covers) or just simple drop in style (rectangular). In the Europe/USA there are often locking bolt/s to fasten the cover.
With the cover the edge of the casing can be seen. Older style models often have much thicker casings - prior to ductile iron being introduced post World War II.
Square, square/round models often have quite wide casings with a small round cover in the middle.
Thankfully due to the nature of the design many old covers have stood the test of time and even after almost one hundred years stiill have distinctive markings and designs. Sometimes these can identify specific plumbers, suppliers or utilities providing the gas and water service.
Many of the old square covers are being replaced with modern ductile iron covers. This is particularly apparent when footpaths/sidewalks are re-surfaced.
In the last five years re-surfacing is now being used to move the location of valve covers. Originally they were located next to the property line. Now they are located near the gutters. The latter makes sense as in the case of emergency it is desirable not to be too near the property for safety reasons.
Grey Iron and Ductile Iron
(From Wikipedia)
Gray iron is the most common cast iron and most widely used based on weight.
It was metal forged at a much higher temperature and was extremely strong - though very heavy.
In the past cast iron was the ‘plastic’ of its time. Used for a wide variety of engineering purposes: in the kitchen - cookers, pots, fountains, lampposts, machinery, steam engines, railways, tools, etc.
It is interesting to note that though Duticle iron is superior the unique qualities of cast iron still make it shelfful for milling machines, ols, etc.
In the catalogue ‘Crevit Iplex Ductile Pipes’ the history of Grey Iron dates from 1455 in Germany. In 1664 King Louis XIX of France used Grey iron pipes for Versailles water fountains. The piping survived 340 years. Grey iron was introduced into the USA in 1817. Because of this early usage many pipes in the USA have been in continuous service for over 100 years.
One of the most important developments in steel was the creation of Ductile iron. This has all the qualities of cast iron coupled with toughness and ductility. Though similar to Grey iron it incorporated casting refinements, additional metallurgical processes and superior quality control.
The main difference between the two is the use of graphite. Grey iron's microstructure consists of flakes, whereas in Ductile iron it is spherical nodules. Reduces formation of cracks. Ductile iron has approximately twice the strength of grey iron (tensile, beam,, bending & bursting). Impact strength and elongation are many times that of grey iron.
Further info:
Ductile Iron Description from Durham Foundry:
http://www.durhamfoundry.com/ductile-iron-castings.html
Cast Iron from Wikipedia:
http://www.wikid.eu/index.php/Cast_iron
Featured image below:
square cover and casing showing hinge - GATIC catalogue 2011
updated 3 Oct 2016
Valve covers have a number alternate names -
Municipal boxes, Inspection covers, Fitzroy box, Stop tap box, Inspection box,
municipal water meter boxes
Note as this an Australian website - footpaths will be used for side-walks.
Valve covers are rather like icebergs. Most of the structure is unseen below the
ground / roadway. See image from DASPYL ... Only the top with lugs could be
seen on footpaths.
There are two sections - the casing and the cover (or top).
The casing is the surrounding structure that protects the stop valves within.
In the past the construction material has been steel and with more modern developments - ductile iron. The latter is a very strong and sturdy form of cast
iron. Extremely suitable for high impact areas such as roadways. Sometimes the casing is a simple affair (such as old square covers) wthere there is four walls and
no base. Others have far more structure - particularly those for roadways where its
needed for stability. Thus small casings on footpaths (with far less wear) would
have smaller below ground structure.
The cover is the top part which is removable. Access can be by hinge (Either visible or hidden. Common with square covers.), a simple locking thread (square/round covers) or just simple drop in style (rectangular). In the Europe/USA there are often locking bolt/s to fasten the cover.
With the cover the edge of the casing can be seen. Older style models often have much thicker casings - prior to ductile iron being introduced post World War II.
Square, square/round models often have quite wide casings with a small round cover in the middle.
Thankfully due to the nature of the design many old covers have stood the test of time and even after almost one hundred years stiill have distinctive markings and designs. Sometimes these can identify specific plumbers, suppliers or utilities providing the gas and water service.
Many of the old square covers are being replaced with modern ductile iron covers. This is particularly apparent when footpaths/sidewalks are re-surfaced.
In the last five years re-surfacing is now being used to move the location of valve covers. Originally they were located next to the property line. Now they are located near the gutters. The latter makes sense as in the case of emergency it is desirable not to be too near the property for safety reasons.
Grey Iron and Ductile Iron
(From Wikipedia)
Gray iron is the most common cast iron and most widely used based on weight.
It was metal forged at a much higher temperature and was extremely strong - though very heavy.
In the past cast iron was the ‘plastic’ of its time. Used for a wide variety of engineering purposes: in the kitchen - cookers, pots, fountains, lampposts, machinery, steam engines, railways, tools, etc.
It is interesting to note that though Duticle iron is superior the unique qualities of cast iron still make it shelfful for milling machines, ols, etc.
In the catalogue ‘Crevit Iplex Ductile Pipes’ the history of Grey Iron dates from 1455 in Germany. In 1664 King Louis XIX of France used Grey iron pipes for Versailles water fountains. The piping survived 340 years. Grey iron was introduced into the USA in 1817. Because of this early usage many pipes in the USA have been in continuous service for over 100 years.
One of the most important developments in steel was the creation of Ductile iron. This has all the qualities of cast iron coupled with toughness and ductility. Though similar to Grey iron it incorporated casting refinements, additional metallurgical processes and superior quality control.
The main difference between the two is the use of graphite. Grey iron's microstructure consists of flakes, whereas in Ductile iron it is spherical nodules. Reduces formation of cracks. Ductile iron has approximately twice the strength of grey iron (tensile, beam,, bending & bursting). Impact strength and elongation are many times that of grey iron.
Further info:
Ductile Iron Description from Durham Foundry:
http://www.durhamfoundry.com/ductile-iron-castings.html
Cast Iron from Wikipedia:
http://www.wikid.eu/index.php/Cast_iron
Featured image below:
square cover and casing showing hinge - GATIC catalogue 2011
updated 3 Oct 2016