Brody
June 1st, 2012, 06:30 AM
For those of you who have some trouble decoding what the abbreviations of standard steel tubing are, this will certainly help.
Bottom line...and generalized:
HREW (or similar) shouldn't, but can be, used for roll cages and roll bars. Many of the roll cage manufacturers, especially in the circle track and street racing applications, sell kits that are made completely from HREW. It is, however, best suited for bumper parts, sliders, rock rails, tire carriers, etc.
DOM tubing is best for roll cages and roll bars, along with other critical applications like custom control arms, track bars, tie rods, and other steering components.
Expect to pay almost twice as much per foot for the DOM, if not more, when compared to the HREW.
As far as thickness goes, the standard thickness for almost all applications is .120 wall or 1/8". Control arms and critical steering components are usually 1/4" wall or heavier stock. Many of these are not even tubing in the heavier duty applications, but solid stock that has been threaded to accept Johnny Joints or Heim Joints.
If, for instance, I am building sliders or rock rails for a heavy 3/4"/1 ton rig that weighs in at over 8,000 (Many of the diesel rigs weight more. Any big full size truck is going to weigh a lot), I usually go with 3/16" stock. Pretty much anything lighter can use the standard 1/8" wall tubing is the frame supports and gusseting is done right.
This information is from this site (THANKS!) and, if you are into ATVs of any kind, you should check them out!
Whats in a name DOM, ERW, HREW (http://www.xxxoffroad.com/index.php?option=com_content&view=article&id=49:whats-in-a-name-dom-erw-hrew&catid=31:general&Itemid=46)
Whats in a name DOM, ERW, HREW
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DOM, ERW, HREW, CREW no these are not parts of your computer. But the steel industry has plenty of its own lingo. Whoda thunk it. Since we get a lot of questions about this (yeah we use a bunch around here) I thought a short primer might help. Why you ask? Well there are a bunch of products out there, primarily Cages, that are made of this stuff and I thought you might like to know what you are buying. First off if you are buying a Cage for your ride ask a few questions.
1: What is this made of?
2: How thick is the material.
This will get you started and if you can remember some of the stuff I'm about to throw at you it might help you decide if the hot deal you are being offered is really a hot deal or simply a cold #@$%.
Here is my $.02 - "You can't go wrong with 1020 DOM!"
Read on to see what this means.
DOM, ERW, HREW...all types of "mechanical tubing", as opposed to pipe. All mechanical tubing is dimensioned by OD and a wall thickness.
DOM is actually not a type of tubing, but a process that is applied to tubing after it is initially constructed. It is Drawn Over a Mandrel...which "cold works" it, giving more exact dimensions, smoother finich, and better allignment of the crystal latice structure. It is NOt seamless tubing, and it started life as some sort of EW (electric welded) tubing. Most commonly, when people say "DOM" they mean 1020 mild carbon steel rolled electric welded tubing that is then drawn over a mandrel.
Other mechanical tubing that is not necessarily drawn over a mandrel can be either hot or cold rolled (i.e. rolled from a flat strip into a tube when either hot or cold) and most commonly available will then be electric resistance welded to form the final tube.
Generally...cold forming and cold working add strength and uniformity to a product, and reduce stress.
So VERY BASICALLY, in terms of strength you usually have, in order:
DOM
CREW (cold rolled electric welded)
HREW (Hot....)
Again...these are all just processes, to fully call out the materil, you need to specify the type of steel...but most commonly we are talking about either 1020 mild carbon steel, or 4130 or 4140 Chromium molybdenum alloy steel or 4340 nickel chromium molybdenum alloy steel.
1020 is normally used in the manufacturing of small-diameter or thin-wall DOM steel tube. DOM is formed from strip and electric-resistance welded, then cold drawn to size. The cold drawing process causes the weld line to virtually disappear.
Typical Mechanical Properties: Tensile strength (ksi) 80
1018 is normally used in the manufacturing of cold drawn and hot finished seamless tube. The production of seamless tube is generally made by piercing a hot rolled bar. Hot finished is generally furnished in the unannealed condition, whereas cold drawn seamless is supplied in the unannealed or S/R annealed conditions, depending on the size.
Tensile strength (ksi) 60
1010 is normally used in the manufacturing of electric-resistance welded tube. The product is available normally in cold rolled strip (16 gauge and lighter), and hot rolled strip (.083" wall and heavier). The product can be obtained in the as-welded condition (flash-in) or in the flash-controlled condition.
Typical Mechanical Properties: Tensile strength (ksi) 45
1026 grade is normally used in the manufacturing of DOM, cold drawn seamless and hot finished seamless. This grade normally furnished over 2" OD, with walls heavier than .156". A variety of thermal treatments can be supplied, depending on the type and size of material.
Tensile strength (ksi) 87
Contnuous (butt welded) pipe process.
The continuous process produces a full range of pipe sizes from only a few different widths of skelp. The coils of skelp, or strip, are fed into the mill and their ends welded together to provide a continuous flow. The strip passes through a pre-heater and into a furnace. The heated strip is shaped into an arc of about 270° in a forming stand before passing into the welding stand. There a nozzle applies oxygen to the edges to further heat them as they are pressed and welded together. The pipe's OD and wall thickness are reduced in a stretch-reducing mill. Pipe is then cut to length, reduced to the required size in a sizing mill and water-cooled before being straightened. It is then ready for finishing
Typical Electric Resistance Welded tube process
Steel strip is unwound from coils and side-trimmed to control width and condition the edges for welding. The strip then passes through a series of contoured rolls which progressively cold-form it into a circular shape. The edges are forced together under pressure and welded by heating the steel to temperatures between 2200° F and 2600° F using copper contacts or coil induction. Weld flash is removed from the the inside and outside surfaces of the newly-formed pipe, and the weld zone is heat treated to ensure homogeneity between the base metal and weld. The weld is subjected to in-line nondestructive testing, and the tube then passes through a series of sizing rolls to attain its precise finished diameter. It is then straightened and cut to the desired finished length.
DOM tube being constructed, starting as ERW and then being drawn over a mandrel.
The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing
Seamless tube construction
The production process for seamless tube begins by heating a steel billet to about 2250° F. The red-hot billet is rotated and drawn by rolls over a piercing rod, or mandrel. The action of the rolls causes the metal to flow over and about the mandrel to create a hollow tube shell. After reheating, the shell is moved forward over a support bar and is hot-rolled in several reducing/sizing stands to the desired wall thickness and diameter. The tube, which has grown significantly in length during the piercing and sizing processes, is then cut into sections and conveyed across a cooling bed to cool slowly in the air. It then receives whatever finishing processes are needed to meet customer requirements.
Steel tubing is usually supplied in one of the following forms:
Seamless Tube.
This is expensive and specialized stuff. It IS NOT the commonly used (and misreferenced) DOM tubing, as DOM tubing does indeed have a seam (albeit, almost invisible - more details below). True seamless tubing is uncommon in 4x4 and automotive use. It is seamless because it is manufactured by a process know as "extrusion" where a solid bar of steel is pierced down the center with a die, at unthinkable pressures, to form a tube. The process looks similar to how hollow pasta (macaroni etc) is made. There are 2 sub-types of seamless tube:
Cold Drawn Seamless (CDS) Tube is normally drawn to O.D. and I.D. dimensions and produced to standard dimensional tolerances (this differs from most other types of tubing except DOM) . It is normally made from SAE 1018 and is considered good quality.
Hot Finished Seamless (HFS) Tube is lower in cost than cold drawn and most applicable where precise dimensions and surface quality are of secondary importance. It is manufactured to O.D. and wall dimensions from SAE 1026 steel and is scaly, less dependable and not as strong as cold drawn tube.
Electric Resistance Welded (ERW) Tube
ERW is the most economical and readily available type of mechanical tuning. It is produced by taking a flat bar of steel and rolling it into a tube shape (picture rolling up a newspaper - but without any overlap) and then welding the seam - by, you guessed it - electric resistance - hence the name. Electric resistance welding is somewhat like a long, continuous spot weld. It's often computer controlled and extremely consistent. ERW is normally SAE 1010 (for wall thickness < 16 ga) or SAE 1020. ERW tube comes in 2 flavours:
Hot Rolled ERW (HREW)
HREW is rolled into a tube at elevated temperatures, usually way above room temperature. This produces a tubing that is more malleable and therefore easier to form but that is also not as strong, is supplied covered with scale, and not as uniform in dimension as cold rolled. It is also quite a bit cheaper than cold rolled.
Cold Rolled ERW (CREW)
CREW is manufactured by a process in which a steel bar is rolled into a tube and the seam welded, usually at room temperature. Compared to hot rolled, CREW is stronger - (greater yield strength) - because of the improvement in the crystal lattice structure from improved grain size, shape, and orientation imparted by being worked at cold (room) temperatures), straighter, has a much smoother and more uniform surface finish, and is made to much tighter, more consistent dimensions. It is the best economical choice for tube work, and because of the better surface finish and tighter dimensional tolerances it is much nicer to work with than HREW.
Drawn Over Mandrel (DOM)
Strong and well-finished DOM is an electric resistance welded tube tested for soundness of weld and drawn through a die and over a mandrel. This process imparts significantly improved mechanical properties to the tube, due to the cold working process. It is considered a high quality tube, and is normally constructed from SAE 1020 or 1026 steel. Note that, technically DOM refers to the process by which the tube is finished after having started as an ERW tube. Technically, DOM is not a type of steel tube, but rather a process. As so often happen though - in common use the term has become accepted to mean a specific type of tubing rather than a process. In this case, when people say "DOM" they normally mean an ERW tube drawn over a mandrel at (close to) room temperature and made from SAE 1020 steel. It is normally drawn to O.D. and I.D. dimensions. Here is what the Steel Tube Institute of North America has to say about DOM:
The DOM Manufacturing Process
The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing.
The cold-drawing process creates a uniform, precision product with substantially improved tolerances, surface finish and tensile strength, increased hardness and good machinability. In this process, the tube is cleaned and annealed, and one end of each length is squeezed to a point so it can be gripped by the drawing mechanism. The tube is then drawn through one or more dies and over mandrels. This reduces the diameter of the tube and thins its walls to the required dimensions in a controlled fashion to provide the qualities desired in the finished product. Metallurgically, drawing improves the tube's concentricity, tensile strength, hardness and machinability. Close dimensional accuracy is achieved through tight control of both outside and inside diameters.
Alloy Steel Tubing
Is not really a different type of tubing, as it will be manufactured by one of the above described methods, usually by extrusion, but from alloy steel instead of mild steel. It is generally available in either the normalized or the annealed condition. Commonly referred to as chrom-moly tube - it has very strict welding process and post-welding heat treatment and stress relieving requirements. It is my opinion that it can (should) only be TIG or Oxy-Acetylene welded, and then only if proper stress relieving will be done post welding. Sure people MIG weld it all the time, and you can safely do so - BUT - what you have in the end is a superior tube with an inferior weld joint which reduces the overall strength of whatever you fabricated to the weakest link (the weld in this case) and so you have a very expensive structure that is no better overall than one made from 1020 DOM.
Exact chemical content, heat treatment, physical properties, production method and therefore mechanical properties will vary from one supplier to the next, even for seemingly similarly named products - the wise fabricator double-checks all assumptions carefully before building anything. Different suppliers will also have available different products. For example, Ryerson-Tull, one of North America's largest suppliers list in their catalogue of steel tubing between 1" and 2' OD, the following types (not all available in all sizes):
CDS, HFS, DOM, ERW, and a proprietary product they call "Ry-Star 512 Extra".
Many suppliers will have such special proprietary products - you will have to check with your supplier for its proprietary product properties and specs.
Whew, after all of that remember this. If you are getting 1020 DOM, life is good, and that hot deal is probably hot.
Bottom line...and generalized:
HREW (or similar) shouldn't, but can be, used for roll cages and roll bars. Many of the roll cage manufacturers, especially in the circle track and street racing applications, sell kits that are made completely from HREW. It is, however, best suited for bumper parts, sliders, rock rails, tire carriers, etc.
DOM tubing is best for roll cages and roll bars, along with other critical applications like custom control arms, track bars, tie rods, and other steering components.
Expect to pay almost twice as much per foot for the DOM, if not more, when compared to the HREW.
As far as thickness goes, the standard thickness for almost all applications is .120 wall or 1/8". Control arms and critical steering components are usually 1/4" wall or heavier stock. Many of these are not even tubing in the heavier duty applications, but solid stock that has been threaded to accept Johnny Joints or Heim Joints.
If, for instance, I am building sliders or rock rails for a heavy 3/4"/1 ton rig that weighs in at over 8,000 (Many of the diesel rigs weight more. Any big full size truck is going to weigh a lot), I usually go with 3/16" stock. Pretty much anything lighter can use the standard 1/8" wall tubing is the frame supports and gusseting is done right.
This information is from this site (THANKS!) and, if you are into ATVs of any kind, you should check them out!
Whats in a name DOM, ERW, HREW (http://www.xxxoffroad.com/index.php?option=com_content&view=article&id=49:whats-in-a-name-dom-erw-hrew&catid=31:general&Itemid=46)
Whats in a name DOM, ERW, HREW
http://www.xxxoffroad.com/images/M_images/pdf_button.png (http://www.xxxoffroad.com/index.php?view=article&catid=31%3Ageneral&id=49%3Awhats-in-a-name-dom-erw-hrew&format=pdf&option=com_content&Itemid=46)
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http://www.xxxoffroad.com/images/M_images/emailButton.png (http://www.xxxoffroad.com/index.php?option=com_mailto&tmpl=component&link=aHR0cDovL3d3dy54eHhvZmZyb2FkLmNvbS9pbmRleC5wa HA/dmlldz1hcnRpY2xlJmlkPTQ5JTNBd2hhdHMtaW4tYS1uYW1lLW RvbS1lcnctaHJldyZvcHRpb249Y29tX2NvbnRlbnQmSXRlbWlk PTQ2)
DOM, ERW, HREW, CREW no these are not parts of your computer. But the steel industry has plenty of its own lingo. Whoda thunk it. Since we get a lot of questions about this (yeah we use a bunch around here) I thought a short primer might help. Why you ask? Well there are a bunch of products out there, primarily Cages, that are made of this stuff and I thought you might like to know what you are buying. First off if you are buying a Cage for your ride ask a few questions.
1: What is this made of?
2: How thick is the material.
This will get you started and if you can remember some of the stuff I'm about to throw at you it might help you decide if the hot deal you are being offered is really a hot deal or simply a cold #@$%.
Here is my $.02 - "You can't go wrong with 1020 DOM!"
Read on to see what this means.
DOM, ERW, HREW...all types of "mechanical tubing", as opposed to pipe. All mechanical tubing is dimensioned by OD and a wall thickness.
DOM is actually not a type of tubing, but a process that is applied to tubing after it is initially constructed. It is Drawn Over a Mandrel...which "cold works" it, giving more exact dimensions, smoother finich, and better allignment of the crystal latice structure. It is NOt seamless tubing, and it started life as some sort of EW (electric welded) tubing. Most commonly, when people say "DOM" they mean 1020 mild carbon steel rolled electric welded tubing that is then drawn over a mandrel.
Other mechanical tubing that is not necessarily drawn over a mandrel can be either hot or cold rolled (i.e. rolled from a flat strip into a tube when either hot or cold) and most commonly available will then be electric resistance welded to form the final tube.
Generally...cold forming and cold working add strength and uniformity to a product, and reduce stress.
So VERY BASICALLY, in terms of strength you usually have, in order:
DOM
CREW (cold rolled electric welded)
HREW (Hot....)
Again...these are all just processes, to fully call out the materil, you need to specify the type of steel...but most commonly we are talking about either 1020 mild carbon steel, or 4130 or 4140 Chromium molybdenum alloy steel or 4340 nickel chromium molybdenum alloy steel.
1020 is normally used in the manufacturing of small-diameter or thin-wall DOM steel tube. DOM is formed from strip and electric-resistance welded, then cold drawn to size. The cold drawing process causes the weld line to virtually disappear.
Typical Mechanical Properties: Tensile strength (ksi) 80
1018 is normally used in the manufacturing of cold drawn and hot finished seamless tube. The production of seamless tube is generally made by piercing a hot rolled bar. Hot finished is generally furnished in the unannealed condition, whereas cold drawn seamless is supplied in the unannealed or S/R annealed conditions, depending on the size.
Tensile strength (ksi) 60
1010 is normally used in the manufacturing of electric-resistance welded tube. The product is available normally in cold rolled strip (16 gauge and lighter), and hot rolled strip (.083" wall and heavier). The product can be obtained in the as-welded condition (flash-in) or in the flash-controlled condition.
Typical Mechanical Properties: Tensile strength (ksi) 45
1026 grade is normally used in the manufacturing of DOM, cold drawn seamless and hot finished seamless. This grade normally furnished over 2" OD, with walls heavier than .156". A variety of thermal treatments can be supplied, depending on the type and size of material.
Tensile strength (ksi) 87
Contnuous (butt welded) pipe process.
The continuous process produces a full range of pipe sizes from only a few different widths of skelp. The coils of skelp, or strip, are fed into the mill and their ends welded together to provide a continuous flow. The strip passes through a pre-heater and into a furnace. The heated strip is shaped into an arc of about 270° in a forming stand before passing into the welding stand. There a nozzle applies oxygen to the edges to further heat them as they are pressed and welded together. The pipe's OD and wall thickness are reduced in a stretch-reducing mill. Pipe is then cut to length, reduced to the required size in a sizing mill and water-cooled before being straightened. It is then ready for finishing
Typical Electric Resistance Welded tube process
Steel strip is unwound from coils and side-trimmed to control width and condition the edges for welding. The strip then passes through a series of contoured rolls which progressively cold-form it into a circular shape. The edges are forced together under pressure and welded by heating the steel to temperatures between 2200° F and 2600° F using copper contacts or coil induction. Weld flash is removed from the the inside and outside surfaces of the newly-formed pipe, and the weld zone is heat treated to ensure homogeneity between the base metal and weld. The weld is subjected to in-line nondestructive testing, and the tube then passes through a series of sizing rolls to attain its precise finished diameter. It is then straightened and cut to the desired finished length.
DOM tube being constructed, starting as ERW and then being drawn over a mandrel.
The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing
Seamless tube construction
The production process for seamless tube begins by heating a steel billet to about 2250° F. The red-hot billet is rotated and drawn by rolls over a piercing rod, or mandrel. The action of the rolls causes the metal to flow over and about the mandrel to create a hollow tube shell. After reheating, the shell is moved forward over a support bar and is hot-rolled in several reducing/sizing stands to the desired wall thickness and diameter. The tube, which has grown significantly in length during the piercing and sizing processes, is then cut into sections and conveyed across a cooling bed to cool slowly in the air. It then receives whatever finishing processes are needed to meet customer requirements.
Steel tubing is usually supplied in one of the following forms:
Seamless Tube.
This is expensive and specialized stuff. It IS NOT the commonly used (and misreferenced) DOM tubing, as DOM tubing does indeed have a seam (albeit, almost invisible - more details below). True seamless tubing is uncommon in 4x4 and automotive use. It is seamless because it is manufactured by a process know as "extrusion" where a solid bar of steel is pierced down the center with a die, at unthinkable pressures, to form a tube. The process looks similar to how hollow pasta (macaroni etc) is made. There are 2 sub-types of seamless tube:
Cold Drawn Seamless (CDS) Tube is normally drawn to O.D. and I.D. dimensions and produced to standard dimensional tolerances (this differs from most other types of tubing except DOM) . It is normally made from SAE 1018 and is considered good quality.
Hot Finished Seamless (HFS) Tube is lower in cost than cold drawn and most applicable where precise dimensions and surface quality are of secondary importance. It is manufactured to O.D. and wall dimensions from SAE 1026 steel and is scaly, less dependable and not as strong as cold drawn tube.
Electric Resistance Welded (ERW) Tube
ERW is the most economical and readily available type of mechanical tuning. It is produced by taking a flat bar of steel and rolling it into a tube shape (picture rolling up a newspaper - but without any overlap) and then welding the seam - by, you guessed it - electric resistance - hence the name. Electric resistance welding is somewhat like a long, continuous spot weld. It's often computer controlled and extremely consistent. ERW is normally SAE 1010 (for wall thickness < 16 ga) or SAE 1020. ERW tube comes in 2 flavours:
Hot Rolled ERW (HREW)
HREW is rolled into a tube at elevated temperatures, usually way above room temperature. This produces a tubing that is more malleable and therefore easier to form but that is also not as strong, is supplied covered with scale, and not as uniform in dimension as cold rolled. It is also quite a bit cheaper than cold rolled.
Cold Rolled ERW (CREW)
CREW is manufactured by a process in which a steel bar is rolled into a tube and the seam welded, usually at room temperature. Compared to hot rolled, CREW is stronger - (greater yield strength) - because of the improvement in the crystal lattice structure from improved grain size, shape, and orientation imparted by being worked at cold (room) temperatures), straighter, has a much smoother and more uniform surface finish, and is made to much tighter, more consistent dimensions. It is the best economical choice for tube work, and because of the better surface finish and tighter dimensional tolerances it is much nicer to work with than HREW.
Drawn Over Mandrel (DOM)
Strong and well-finished DOM is an electric resistance welded tube tested for soundness of weld and drawn through a die and over a mandrel. This process imparts significantly improved mechanical properties to the tube, due to the cold working process. It is considered a high quality tube, and is normally constructed from SAE 1020 or 1026 steel. Note that, technically DOM refers to the process by which the tube is finished after having started as an ERW tube. Technically, DOM is not a type of steel tube, but rather a process. As so often happen though - in common use the term has become accepted to mean a specific type of tubing rather than a process. In this case, when people say "DOM" they normally mean an ERW tube drawn over a mandrel at (close to) room temperature and made from SAE 1020 steel. It is normally drawn to O.D. and I.D. dimensions. Here is what the Steel Tube Institute of North America has to say about DOM:
The DOM Manufacturing Process
The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing.
The cold-drawing process creates a uniform, precision product with substantially improved tolerances, surface finish and tensile strength, increased hardness and good machinability. In this process, the tube is cleaned and annealed, and one end of each length is squeezed to a point so it can be gripped by the drawing mechanism. The tube is then drawn through one or more dies and over mandrels. This reduces the diameter of the tube and thins its walls to the required dimensions in a controlled fashion to provide the qualities desired in the finished product. Metallurgically, drawing improves the tube's concentricity, tensile strength, hardness and machinability. Close dimensional accuracy is achieved through tight control of both outside and inside diameters.
Alloy Steel Tubing
Is not really a different type of tubing, as it will be manufactured by one of the above described methods, usually by extrusion, but from alloy steel instead of mild steel. It is generally available in either the normalized or the annealed condition. Commonly referred to as chrom-moly tube - it has very strict welding process and post-welding heat treatment and stress relieving requirements. It is my opinion that it can (should) only be TIG or Oxy-Acetylene welded, and then only if proper stress relieving will be done post welding. Sure people MIG weld it all the time, and you can safely do so - BUT - what you have in the end is a superior tube with an inferior weld joint which reduces the overall strength of whatever you fabricated to the weakest link (the weld in this case) and so you have a very expensive structure that is no better overall than one made from 1020 DOM.
Exact chemical content, heat treatment, physical properties, production method and therefore mechanical properties will vary from one supplier to the next, even for seemingly similarly named products - the wise fabricator double-checks all assumptions carefully before building anything. Different suppliers will also have available different products. For example, Ryerson-Tull, one of North America's largest suppliers list in their catalogue of steel tubing between 1" and 2' OD, the following types (not all available in all sizes):
CDS, HFS, DOM, ERW, and a proprietary product they call "Ry-Star 512 Extra".
Many suppliers will have such special proprietary products - you will have to check with your supplier for its proprietary product properties and specs.
Whew, after all of that remember this. If you are getting 1020 DOM, life is good, and that hot deal is probably hot.