STAINLESS STEEL CORRUGATED HOSES
There are many components in a metal hose assembly and care should be taken when selecting each of them. Moreover, the components have their own unique technical limitations so it is important to make sure each of the components is compatible with your application. In much the same way as a “chain is as strong as its weakest link”, a metal hose assembly will only perform to the limits of its weakest component.
Once the components have been selected, the quality and skill of the fabricator assembling the components becomes important. The procedures and care used when fabricating assemblies also has a dramatic effect on the assembly’s overall performance.
Glory has invested a considerable amount of resources to researching metal hose fabrication and developing a state-of-the-art fabricating center. In addition, we share the welding technology we have developed with our fabricating distributors. All of this is done to promote quality and consistency in fabricating metal hose assemblies.
.To properly design a metal hose assembly for a particular application, the following design parameters must be determined. To help remember them, they have been arranged to form the acronym “S.T.A.M.P.E.D.”
Size – The diameter of the connections in which the assembly will be installed is needed to provide a proper fit. This information is required.
Temperature – As the temperature to which the assembly is exposed (internally and externally) increases, the strength of the assembly’s components decreases. Also, the coldest temperature to which the hose will be exposed can affect the assembly procedure and/or fitting materials. If you do not provide this information it will be assumed that the temperatures are 70° F.
Application – This refers to the configuration in which the assembly is installed. This includes both the dimensions of the assembly as well as the details of any movement that the assembly will experience. This information is necessary to calculate assembly length and required flexibility.
Media – Identify all chemicals to which the assembly will be exposed, both internally and externally. This is important since you must be sure that the assembly’s components are chemically compatible with the media going through the hose as well as the environment in which the hose is installed. If no media are given, it will be assumed that both the media and the external environment are compatible with all of the available materials for each component.
Pressure – Identify the internal pressure to which the assembly will be exposed. Also, determine if the pressure is constant or if there are cycles or spikes. This information is important to determine if the assembly is strong enough for the application. If no pressure is given it will be assumed that the pressure is low and there are no pressure surges or spikes.
End Fittings – Identify the necessary end fittings. This is required since fittings for the assembly must be chosen to properly fit the mating connections.
Dynamics – Identify the velocity at which the media will flow through the assembly. Since corrugated metal hose does not have a smooth interior, rapid media flow can set up a resonant frequency that will cause the hose to vibrate and prematurely fail. If no velocity is given, it will be assumed that the velocity is not fast enough to affect the assembly’s performance.
Glory’s Proprietary Corrugation Process:
A. Tube
The manufacturing process of corrugated metal hose starts with stainless steel strip that is rolled and the edges welded together to form a thin-walled, gas-tight tube. Glory offers:
High quality steel Strip
Rolled steel to form a tube
B. Hose
After the tube has been welded, corrugations are formed into the tube to make it flexible. There is annular corrugation profiles
Annular Profile
Independent corrugations, straight and parallel
Metal hose is more versatile than other hose in that virtually any fitting can be attached to metal hose. Other types of hose require special shanks and collars in order to attach fittings. For metal hose, any fitting made from a weldable material can be attached without the need for special features. This versatility also means that multiple fittings can be welded together to make custom solutions for difficult applications.
Selecting the proper fittings for an application is largely determined by the mating fittings to which the hose assembly will be attached. Once the mating fittings have been identified, the hose fittings should complement the mating fittings in type, size, and alloy. Even though the selection of hose fittings is determined by the mating fittings, it is a good idea to confirm that the fittings used in the application are appropriate for the application and any necessary changes made. Ensure that the fittings are chemically compatible with and are able to withstand the pressure and temperatures of both the media and the surrounding environment.
The following show commonly used fittings for corrugated metal hose assemblies. Please contact Glory’s Customer Service Department for end connections that are not listed.
Male Pipe Nipple
Alloys – T304 and T316 Stainless Steel, Carbon Steel, 276
Sizes – 1/8″ thru 12″
Schedules – 40 and 80
Hex Male
Alloys – T304 and T316 Stainless Steel, Carbon Steel, Brass
Sizes – 1/4″ thru 4″
45° and 90° SAE Fitting (JIC)
Alloys – Stainless Steel, Carbon Steel
Sizes – 1/2″ thru 2″
Flanges
Alloys – T304 and T316 Stainless Steel - Carbon Steel
Sizes – 1/2″ to 100"
Type - Avaliable All Types Of Flanges
Class - available All Class
Part A and Part D (Cam-Lock)
Alloys – T316 Stainless Steel, Brass, Aluminum
Sizes – 1/2″ thru 8″
Available All Camlock Types
Tube End
Alloys – T304, T316, and T321 Stainless Steel, Carbon Steel
Sizes – 1/8″ thru 8″ (seamless and welded)
Wall Thickness – various
Short and Long Radius Elbows (45° and 90°)
Alloys – T304 and T316 Stainless Steel, Carbon Steel, 276
Sizes – 1/4″ thru 6″
Reducer
Alloys – T304 and T316 Stainless Steel, Carbon Steel
Sizes – 3/4″ thru 6″
Schedule – 10 to 40 Carbon Steel - Stainless steel
Specialty Gas Nuts
Alloys – Brass
Sizes – A, B, C, D
Thread Type – SAE and BSP
To calculate the proper length of a hose assembly:
Verify that the installation is properly designed
You can see our illustration of the right and wrong ways to install a hose assembly. Basically, there are three considerations:
Do not torque the hose.
Do not overbend the hose.
Do not compress the hose.
Calculate the live length of the assembly
The live length of the assembly is the amount of active (Flexible Hose) in an assembly; that is, the hose between the braid collars.
Calculate the overall length of an assembly
Overall length is equal to the live length plus the lengths of the braid collars and fittings. When adding fitting lengths be aware that the points from which measurements should be taken vary for different fitting types. When calculating overall length for assemblies with threaded fittings, remember to account for the length of thread that is lost by threading into the mating connection.
JIC/SAE type fittings are measured from the seat of the fitting.
Elbows and other fittings with a radius are measured from the Centerline of the fitting.
Flanges are measured from the flange face or from the face of the stub end if one is used.
Threaded fittings are measured to the end of the fitting.
Metal Hose assemblies often require special accessories or components in order to provide long service life in severe applications or make the assemblies easier to use. There are many accessories that may be specified including:
Guard, made from metal and other materials, can be provided to protect an assembly from overbending, abrasion, impact, and thermal damage.
Jacket and tracer hoses are incorporated into corrugated hose assemblies in order to keep certain media at elevated or reduced temperatures so that it can be easily conveyed.
A sacrificial bronze braid can be inserted between the hose and the stainless steel braid to improve cycle life.
One or several accessories can be easily combined with an assembly to more efficiently transport media, protect the assembly, or both.
The following pages list some common accessories along with a brief explanation of the benefits each accessory offers. This is not an exhaustive list of all possible accessories. Please contact Glory Customer Service Department with your specific requirements.
Spring Guard
When there is potential for damaging an assembly in service, a guard can be easily installed during fabrication. This type of guard consists of a metal spring that is attached behind the fitting. The style of guard can be tailored to meet the application and the type of hose.
Protective Cover
If the potential for impact or high temperature damage is not severe, or if the additional weight and bulk of a full metal guard is unacceptable, rubber or plastic scuff guards can be installed to protect the corrugated hose and braid.
Insulating Jackets
If the corrugated hose is to convey hot media, and there is a potential for skin contact, an insulated, protective jacket is available. The jacket consists of a tubular banded fiberglass insulation, covered and impregnated with silicone rubber. The jacket is installed over the corrugated hose and metal banded in place. The jacket can also be used to insulate the corrugated assembly and either prevent ambient heat from being conveyed to the media or to reduce heat loss .
Liners
An interlocked hose or liner is often installed inside a corrugated hose assembly. The liner commonly serves two additional purposes, while still maintaining the full working pressure of the corrugated hose. The first is to protect the hose corrugations from excessive media velocities. Media speeds can induce resonant vibrations in the corrugations causing rapid fatigue and subsequent fracturing of the hose wall. The liner provides a relatively smooth surface for the media and, by avoiding the media impacting on the corrugation valleys, reduces the chances of harmonic resonance. The second purpose for a liner is for abrasion resistance. Even slightly abrasive media flowing at medium to high speeds can cause premature wear of the corrugated hose interior surfaces. The liner provides a smooth flow path as well as a relatively thick layer of abrasion resistant metal between the media and the corrugated hose. The liner will also help reduce pressure loss due to friction between the media and corrugated hose. Proper fit between the hoses is essential for good performance.
Armor Guard / Bend Restricter
Applications in which the corrugated hose is subject to external abrasion, molten material splash, or impact damage may require a protective armor or guard along all or a portion of its length. A guard is typically made from interlocked or squarelocked metal hose and is welded to the assembly. Note that the bend restricter has a bend diameter equal to or greater than the corrugated hose it is protecting.
Jacketed Assemblies
A jacketed assembly consists of a “ hose within a hose ” An inner or primary media conveying hose is enclosed or jacketed by a larger diameter hose. The hoses are joined at each end by specially designed fittings so that there is no media pathway between the two hoses. Jacketed assemblies are often specified when the primary media must be kept at either an elevated or cryogenic temperature. Steam is often circulated through the jacket hose to keep a viscous material in the inner hose hot and easily conveyed. A vacuum can also be pulled on the jacket hose to insulate cryogenic liquids being conveyed in the inner hose.
Tracers
Traced assemblies are similar in concept to jacketed assemblies in that there is an inner, smaller diameter hose encased by a single larger diameter hose. Where jacketed assemblies surround the media with heat or cold, traced assemblies have the media surround the hose containing the heating or cooling element. The tracer, or inner hose, may also be installed in a long “U” shaped loop within the outer hose, with the steam inlet and outlet at the same end of the assembly