Ways to Maximise Metal Hose Service Life




Metal hose installation should follow a proper guideline to ensure its optimum lifetime performance and minimize risk to workers and equipment. This blog aims to highlight some necessary steps that aids in maximising your hose life, especially in metal hoses.

1. Proper Hose Length


Metal hose assembly should have more length than its port to port distance as hose can elongate and contract when pressurized. The contraction will add more stress to the assembly and might lead to catastrophic failure such as leak, loose fitting and hose failure. In addition, having too much length will also give adverse effect as it might introduce new problems such as hose abrasion and uncontrolled hose movements.

2. Proper Placement


Proper placement can prolong metal hose life significantly. Below are the correct ways to place your hose:

1. Avoid Stacking – Avoid adding extra load such as valve or piping onto your hose as it might crush the hose underneath.

2. Store it Safely – Make sure your hose is installed away from potential risk and hazards that can damage the hose (e.g heat, chemical or corrosion).


3. Protection Against Extreme Temperature Change


Extreme temperature can cause tears and cracks to your hose. Avoid direct contact between the hose and heat source or use additional protection such as protective sleeves to protect your hose.

4. Avoid Torque


When your metal hose is torqued/twisted, it has a higher chance of failure as hose is not designed to withstand torsional force. During installation, use swivel fitting on one end and fixed end on the other end and always make sure the assembly has only one plane of flexing to avoid torsional stress. In addition, proper tightening will eliminate torque movement during the hose operation.

5. Avoid Over or Sharp Bending


Bending metal hose into a radius smaller than its Minimum Bending Radius (MBR) could result in hose failure. Provide enough length, use elbow/pipe bend to avoid sharp bend and use support such as a suspension to avoid hose sagging. Check bending radius on datasheet before installing.

6. Avoid Abrasion


Hose abrasion occurs because of constant contact between hose and abrasive surface. It can lead to hose failure as it gradually weakens the hose’s pressure retention. Introduce external protective cover such as spring guard, metal guard, etc to help minimize the friction or avoid dragging the hose on a rough surface to avoid abrasion.

7. Avoid Axial Overextension and Compression


Hose should not be stretched or compressed along its longitudinal axis. Axial overextension and over compression will damage the hose as it is not designed for in-line axial movement. Add a support to properly guide the hose routing or install the hose perpendicular to the direction of the movement.

8. Proper Grounding

Some fluid may contain solid impurities that if it is constantly rubbing the hose, it will create an electric charge on the hose surface. Establish a proper grounding route to prevent electrical discharge to the workers or equipment in near proximity of the hose.

9. Maintain Hose Cleanliness


Impurities such as debris, dust, rust and abrasive particles will accumulate during assembly step and after usage. The impurities can lead to serious wear and tear damage to the Stainless-Steel hose; therefore, immediate cleaning after assembly and after usage are highly recommended. The cleaning is done by flushing or rinsing all the impurities by using cleaning media such as:

  • Strong compress air blast
  • Sponge-like projectiles
  • Cleaning liquids

Final Word

More? Please contact us at (65) 6298 3211 or enquiry@wahjooseng.com. Click here to check our hose collections or general hose installation guidelines.

Function of Stainless Steel Braids


Stainless steel hose braid serves as the “flexing muscle” to resist internal and external pressure and to provide protection against abrasion and contamination When compared to non-braided hose, braided hose can prevent longitudinal expansion and protect the hose’s shape and flexibility (Wikipedia, 2018). It is also highly flexible and can mould itself to follow the movement of the hose  (S. Hasan, 2018).


Stainless steel hose braids come in a variety of choices that caters to specific needs or applications. Materials available upon request includes:

  • 304L, 316L and 321 Stainless Steel
  • Bronze
  • Monel 400
  • Hastelloy C276
  • Inconel alloy 625


Multiple layers of braid are frequently used to enhance the strength and coverage of hose assembly (The Association for Hose and Accessories Distribution, 2015); Hence, hose with more braid layer is used for high-pressure application. Below chart shows the working pressure of different number of braid layers:


However, the weight of the assembly shall increase with the number of braid layers. Check out the application’s pressure requirement to make sure you use the right number of braids.


Wah Joo Seng provides customised quality braided metal hose assemblies in an assortment of materials, sizes, braid layers and various types of end connections to suit different applications. Our assemblies are painstakingly done locally in-house. Drop us an email at enquiry@kingflex.com or call+65 62983211 to find out more. We love to hear from you!

Looking for more? Browse through our products here or check out more of our stainless-steel hose articles


The Everything Hose. Almost.


With so many types of hoses that are available in the market, choosing a right hose that suits your application can be a mind boggling and/or fogging issue. PVC? Rubber? Fabric? Composite? Metal? Pipes? Wire? Non-wired? Suction or Delivery? WHAT!?

There is not a definite RIGHT type of hose to use or purchase, it all boils down to what application are you going to use it with.

Stainless steel hoses remain a very popular choice for fluid transfer or control applications. They are used in a wide range of industries such as food processing, biomedical, oil and gas, chemical plants etc. They are available in several different grades/alloys to better suit different applications.

So, when do you really need metal hoses? Consider these criteria below when choosing a metal hose:

1. Stainless Steel Hose has Good Mechanical Properties

Stainless Steel hose has good versatility, durability and outstanding price-to-quality ratio. As a metal, it is tough, malleable, formable, strong and modifiable; it is also a good fit for extreme pressure and temperature applications and to protect plant and worker from harm and potential catastrophic failure.


Above charts compare the properties of one of our Stainless-Steel hose (Kingflex® Series P3 with single braid) to the average property value of various rubber and PVC hoses. Clearly, both charts show that Stainless Steel hose has a much better mechanical properties than rubber or a PVC hose type.

Mechanical properties of Stainless-Steel hoses can be enhanced by layers of braids, pitch and wall thickness.

2. Stainless Steel Hose has excellent Chemical Resistance Properties

Stainless steel is a chemical resistance metal that can convey corrosive chemicals. This special property serves as one of the main driving factors for its high demand.

Different from normal steel/carbon steel, Stainless Steel has a 1-3nm (Hedberg & Wallinder, 2016) thin passive oxide layer that protects the underlying iron (Fe) from being oxidised. The special layer creates the chemical resistance property of the stainless steel we know (Brytan, 2016).


If we compare Stainless Steel’s chemical resistance to Carbon Steel, the metal has more A and B and less C and D rating than Carbon Steel (CS). This shows that Stainless Steel has better chemical resistance than Carbon Steel (Habonim, 2013).

3. Stainless Steel Hose Does Not Allow Gas Permeation

Gas permeation is the penetration of a gas through a solid. Stainless Steel and metal hose are not susceptible to gas permeation. This property is important if the gas media needs to be contained or if high purity product is desired. The rate of permeation depends on the size of the gas molecule; smaller gas molecule will have a faster permeation rate.

4. Stainless Steel Hose Handles Full Vacuum

Stainless Steel Hose can maintain its shape and form in the event of suction/vacuum. Non-metal hoses typically will collapse in negative pressure and in the absence of support. Hose collapse will damage the hose and risk the safety of the workers and surrounding amenities.

5. Stainless Steel Hose Has Great Flexibility

Stainless Steel Hose can incorporate any type and configuration of weldable fitting into their assembly while other hose types might require some special shanks or ferrule. This benefit can simplify the assembly, increase its pressure rating and reduce potential leakage points.

6. Stainless Steel Does Not Build Static Discharge

Since Stainless Steel is a strong conductor, it does not build-up static charge. This provide greater safety for the metal hose as static charge can be easily grounded (Production Automation Corporation, n.d.). Non-conductive hose like rubber hose hinders the electron flow, allowing it to accumulate and be discharged. Static discharge might be lethal depending on the situation.

With so many advantageous traits to it, stainless steel hose does sound like it is ALMOST a everything hose. But oh wait, WHEN AND WHERE NOT TO USE stainless steel hoses?

BONUS. When and Where Not Use Stainless Steel Hose

Stainless steel is still a metal alloy, which can corrode especially in chloride and reducing environment (Hedberg & Wallinder, 2016).The introduction of reducing agent will attack the passive layer which will lead to local corrosion such as pitting or crevice corrosion.

It is best to avoid using SS Hose when it is in a reducing environment such as with Hydrochloric acid (HCl), Sulfuric Acid (H2SO4), condensed molten salt, alkali sulphate and alkali chlorides.

Stainless Steel grade for example in the case of SS316 introduces new elements: Molybdenum (Mo) or Nickel (Ni) that offers protection in reducing environment and a better chemical resistant property for the respective grade. Other grade that does not introduce these elements like SS304 however will have lower chemical resistance (The International Nickel Company, 1982).


Wah Joo Seng provides customised high quality braided metal hose assemblies in an assortment of materials, sizes, braid layers and various types of end connections to suit different applications. Our assemblies are painstakingly done locally in-house. Drop us an email at enquiry@kingflex.com or call+65 62983211 for a non-binding, personalized metal hose solution. We love to hear from you!

Looking for more? Browse through our products here .

Types of Flange Facings


In our previous blog, we talked about the most common flange types used in the industry. Today, we would like to discuss on another important aspect of a flange – flange face. Understanding flange faces plays a crucial role to ensure that the right fit, right gasket and safety can be applied.

Flange face is the surface where contact between two flanges occur. A sealing component is generally introduced between the mating surface, such as metal or gasket. Below is a compilation of flange facing types that are commonly recognized in the market.

1.     FLAT FACE (FF)

Flat Face

As its names suggest, flat face flange has a flat face. This means that the gasket seat is on the same plane as bolting circle face. Flat face allows full contact across the whole face of the two mating flanges and uses full face gasket. Flat Face flange is used for equipment made from cast iron or other brittle materials hence is only applicable for low temperature and low-pressure applications. It is important to only mate flat face flange with flat face flange and not a raised face.

2.      RAISED FACE (RF)

Raised Face

Most widely used flange. Raised face flange has a small raised ring area around the bore where the gasket will be seated. Raised face flange can concentrate more pressure on a smaller gasket area and increases the seal and flange’s joint pressure containment capability. Raised face is typically used for equipment made from forged steel.

The height of the raised face depends on the flange’s pressure class rating. Pressure class 150 and 300 will have the height of raised face approximately 1.6mm (1/16 inch) while pressure class 400, 600, 900, 1500 and 2500 will have the height raised to approximately 6.4mm (1/4 inch).


RTJ Flange

Ring type joint (RTJ) flange has an embedded circular grove on its raised face where gasket will seat. When two RTJ flanges are bolted and tightened together, the gasket inside the flange groove will be compressed and will form a tight metal to metal seal. Other benefit of RTJ flange is that the raised face protects the gasket from over compression. RTJ flange has a good pressure and temperature resistance and used for highly demanding applications.

RTJ uses a metallic sealing ring gasket that is suitable for high pressure and high temperature. The gasket comes in either oval or octagonal cross-sectional area. The latter has a better sealing property than the former but only applicable for latest flange design.

4.     TONGUE & GROOVE (T&G)

Tongue and Groove Flange

Tongue and groove (T&G) flange consist of two parts: tongue and groove. The tongue has a raised surface while the groove has a matching depression (groove) machined to its face. Both parts need to be matched to seal connection. Tongue and groove can self-align and has a good sealing property.


Male and Female Flange

Male and Female face (M&F) has similar design with T&G except that its raised surface and groove’s ID extend into the bore hole. The male face is commonly mistaken as a raised face due to their similarities. The typical depth of the female groove is 3/16 inch while the typical height of the male raised face is ¼ inch.

Both tongue and groove and male and female have good sealing and accurate gasket compression. Their downside is their high cost due to lack of commercial availability.


If you are looking for any flanges, you may want to contact us at (65) 6298 3211 or enquiry@wahjooseng.com. Wah Joo Seng can assemble, deliver and supply our hose assemblies with flanges!  Check out our flange collections here!





Flanges Like No Other

Flanges are used in many industries as a quick and economical joint for easy access, cleaning or modification for their equipment or lines. PVC, Carbon Steel, Cast Iron and Stainless Steel are commonly used materials in modern pipe infrastructure. However, the demand for better material has been increasing since the 1930s to fulfil the call for flanges with high level of corrosion resistance and functionality.

In order to address specific concerns especially for applications such as;

  • Chlor-Alkali
  • Bleaches
  • Solvents
  • Acid
  • Caustic

Wah Joo Seng is pleased to present our latest revolutionary flange that performs like no other – Durcor® flanges. These made in U.S.A flanges are proven to be the strongest, lightest and most chemically resistant. This flange combines the benefits of PVC, PTFE and steel. It gives you maximum protection while helping you to save more in the long run.

Durcor® Composite Flange
Durcor® flange is by far the strongest, lightest and most chemically resistant flange.


Durcor® is as light as plastic
You don’t have to break a sweat while carrying Durcor® products.

A special composite compound is at the core of Durcor® flanges, making them featherlight that aids in easy transportation and installation. Durcor® flange weighs similarly to PVC flange and just a fourth of the weight of stainless steel or carbon steel flanges.

Durcor® is relatively lighter when compared to other flanges
Flanges Weight Comparison Chart


Chemical Resistant

Durcor®’s backbone material, vinyl ester resin, can withstand aggressive chemicals and hostile atmospheres such as acid sprays, bleach, salt water and chlorides. Durcor®’s chemical resistance outperforms stainless and ductile iron flanges in both corrosive and non-corrosive environment.

Durcor® vs Carbon Steel Flange
16 hr exposure to 3:1 HCL/HNO3 bottom flange submerged
Durcor® chemical resistance test result
Result after 16 hours


Durcor® has tensile and compressive strength that is comparable to steel; followed by an outstanding impact resistance, Durcor® flange is claimed to be virtually indestructible. Its reinforcing fibers are long and interlocked which allows a systematic load distribution throughout the entire matrix when it is pressurized. Durcor® flange is 8 times stronger than PVC flange and just a slightly less than stainless steel or carbon steel. Furthermore, Durcor® flanges are ANSI B16.5 classified and available in Class 150lbs or Class 300lbs ratings.

Durcor® Tensile Strength Comparison
Tensile Strength Comparison

Other Benefits

Made is USA

Durcor® is made by following US standard
Durcor® Flange is Made in USA

Durcor® flanges are made according to U.S. strict manufacturing standard, using top quality raw materials.

Wide Temperature Range

Durcor® flange has a working temperature range of -60oF to 300oF (-50 oC to 150 oC). Making it suitable for a wide range of application.

Cost Reduction

Though Durcor® is higher in capital costs, their cost-efficiency benefits outweigh the cost in the long run thanks to their unique features.  Benefits of using Durcor® flanges include eliminating the need to install additional support, no painting required, zero corrosion rate, reduce the costs of maintenance, transportation, installation and prolonging service life.

Durcor® Total Cost Comparison
Total Cost Comparison of Durcor® vs other Flanges

Durcor®’s flange type

Our Durcor® Lap Joint flanges are available in Class 150lbs or Class300lbs. Lap Joint flange allows for quick bolthole alignment of the mating flange during installation without taking the extra precautions required during prefabrication of a welded flange.

If you’d like to learn more about different types of flanges, check our blog here.

If you are interested in Durcor® flanges and or pipes, call us at (65) 6298 3211 or drop us an email at kingflex@wahjooseng.com.

Looking for other things? Check out our website here.


Types of Flanges

Flange connection is one of the most commonly used joining method in the industry to connect pipes, valves, pumps, hoses and other equipment. It is often chosen because it is simple and convenient to use. Flange connections provide easy access for cleaning, inspection or modification. Connection or joint is made when two flange faces are aligned, brought together and tightened with bolts and nuts. Below is the detailed breakdown of a flange connection.

Flanges diagram

Based on the diagram above, flange connection can be broken down simply into flange faces, gasket and bolts & nuts.

Choice of flanges is largely dependable on;

  • Types/Standards ASME B16.5 and/or B16.47 etc.
  • Contact Surfaces (Raised Face, Flat Face, Ring Type Joint and etc)
  • Pressure Ratings (150lbs, 300lbs, 400lbs, 600lbs, 1500lbs and 2500lbs)
  • Design Temperature
  • Materials (Forged steel, Stainless steel, PVC, Special Materials)
  • Sizes and Wall Thickness (Schedule)


Lap Joint Flange

Lap Joint Flanges

Lap joint flange consists of 2 main parts: stub end and loose flange. The stub end will be welded to the pipe/fitting while loose flange will slip over the pipe and roam freely. Lap joint flange provides great flexibility for the assembly as it has the freedom to swivel and It is easy to line up.

Lap joint flange is suitable for application that requires frequent dismantling and lower pressure.

Weld Neck Flange

Weld Neck Flanges

Weld neck flange is characterized with a long-tapered neck/hub which then strongly welded with pipe. The neck/hub grows wider from the welded end to the flange face. Because the bore of both the pipe and hub matches, creating a seamless flow path, erosions and turbulences can be greatly reduced. Weld neck flange is a great fit for higher pressure and higher temperature application.

The downside of weld neck flange is that it is bulkier and relatively higher in cost.

Socket Weld Flange

Socket Welded Flanges

Socket weld flange has a female socket inside its bore hole as the resting place for the inserted hose. Socket weld flange is suitable for low pressure and low temperature application. A gap of 1/16” (shown by x) between the hose end and the socket needs to be maintained to reduce residual stress that could occur during solidification of the weld metal. The flange and the hose will then be welded together.

Slip-On Flange

Slip On Flanges

Similar like socket weld flange, slip-on flange has a bore hole in which hose can slip-on. The only different is that slip-on flange does not have a female socket for the hose to rest. Slip-on flange has lower strength when compared to weld neck flange.

Blind Flange

Blind Flanges

Blind flange entirely blank off the hose end to terminate the fluid flow and isolate the piping system. Blind flange is applicable for high pressure.

Threaded Flange

Threaded Flanges

Threaded flange uses thread to secure the connection between the hose and the flange. It is fast, simple and easy to assemble or disassemble.

However, threaded flange is only applicable for low pressure and the threaded pipe needs to be relatively thicker to form the thread to screw on.

In Summary

Types of Flanges Characteristics
Lap Joint Flange ·         Consists of stub end and lap joint flange

·         Flange can roam and rotate freely

·         Applicable for low pressure

·         Easy to install and dismantle

·         Flange does not touch the fluid, hence can be salvaged

Weld Neck Flange ·         Long tapered neck/hub as a strong support

·         Suitable for higher pressure and temperature

·         Bulky and relatively costlier

Socket Welded Flange ·         Slip in bore hole in the centre

·         Bore hole has a female socket in which a pipe is fitted

·         Applicable for low pressure and temperature application

Slip-On Flange ·         Slip in bore hole in the centre

·         Applicable for low pressure

Blind Flange ·         Blank off end to terminate flow

·         Applicable for high pressure.

Threaded Flange ·         Threading inside of flange bore hole

·         Hose has thick wall thickness

·         Easy to connect/disconnect

·         Applicable for low pressure

Final Word

If you are looking for any of these flanges, you may like to contact us at (65) 6298 3211 or enquiry@wahjooseng.com. Wah Joo Seng can assemble, deliver and supply our hose assemblies with flanges!  Check out our flange collections here!


Hardhat Engineer.



Why Task-Line® Gasket is Different?

Introduction to Gasket

Gasket is a seal that fills the space between 2 or more in-contact surfaces to prevent leaks and spills from or into the surfaces while being compressed.

Gasket can be classified in many ways: by material, function, sector/industry. It is important to choose the right gasket for your application to avoid safety or equipment risk. To know more about gasket, read our blog: “Types of Gasketshere.

Introduction to Task-Line®

Task-Line® is a unique PTFE gasket with SS304 insert. Virgin PTFE is molded around and through SS304 perforated metal insert before goes through oven sintering. It is blowout-proof, creep-resistant and tightly seated (no bolt-retorquing). The metal filler enhances its hardness, compressive strength and dimensional stability, making Task-Line® is safer and more durable than the normal gasket.

In addition, Task-Line utilizes PTFE, one of the high-performance materials in the industry. PTFE protects flange joints from almost all aggressive chemical, providing maximum protection for your workers and equipment. Moreover, PTFE is non-stick, non-wettable, and thermal-resistant.

Task-Line® is manufactured in the U.S. and is designed to comply with a proprietary and FDA approval process. Every Task-line® gasket has undergone 15,000-volt spark test to ensure that they are pinholes free!

Summary of Task-Line®

Task-Line® is a PTFE gasket with a revolutionary design that resulted in various benefits such as:

  1. Durability

The SS304 insert provides a higher pressure rating that prevents tear when under pressure.

  1. Reusability

Task-Line® gaskets are leak-free and bubble tight and can be used over and over without sacrificing sealing ability. Furthermore, its high durability also supports its reusability.

  1. Chemical Resistant

Task-Line® gasket is chemically resistant to all acids, all chlorides, sulphates, bleach solutions, solvents, phenols, caustics and peroxides.

  1. Prevent Bolt Retorquing

The metal insert prevents radial flow of the gasket, makes it difficult for bolt retorquing to occur, hence maintaining a tight seal even through repeated temperature cycles. Moreover, the strength of the metal insert also provides a critical blowout-proof protection.

  1. Creep or Cold Flow Resistance

PTFE Encapsulated metal insert restricts the PTFE from cold flow/creep while under load. Giving itself a longer lifespan.

  1. Wide Temperature Range

Task-line® gaskets are stable enough for cryogenic use up to 400oF/204oC.

  1. Self-aligning and Self-Seating

Task-Line® offers quick and simple installation because it can self-align and seat easily to any flange in almost any condition.

  1. Non-Stick

Due to PTFE’s non-stick property, Task-Line® gasket can be released from flanges easily during disassembly without scraping.

Why Should We Use Task-Line®?

Wah Joo Seng’s Task-Line® is made to overcome many challenges that other gaskets face. See how it outperforms other gaskets that you might know.

Virgin PTFE Gasket vs Task-Line®

Gasket made from virgin PTFE
Virgin PTFE Gasket
Virgin PTFE Gasket versus Task-Line® Gasket

Task-Line® PTFE Gasket
Task-Line® PTFE Gasket

Virgin PTFE makes a wonderful gasket; but it lacks hardness, creep-resistance and pressure rating due to the lack of metal insert. Task-Line® Gasket offers all the benefits of blowout-proof protection, creep resistance and prevent bolt retorquing by including SS304 perforated metal insert.

Spiral Wound Gasket vs Task-Line®

Strip Wound Gasket
Spiral Wound Gasket
Other Gasket versus Task-Line® Gasket

Task-Line® PTFE Gasket
Task-Line® PTFE Gasket

Task-Line® gasket has better durability and reusability than spiral wound/stripwound gasket. This makes Task-Line® more economical since Spiral Wound gasket is only applicable for one-time usage.

Sheet Gasket vs Task-Line®

Sheet Gasket: Gasket made by sheet of material
Sheet Gasket
Other Gasket versus Task-Line® Gasket

Task-Line® PTFE Gasket
Task-Line® PTFE Gasket

Like virgin PTFE gasket, sheet gasket lacks metal insert hence it is more susceptible to blowout, bolt retorquing and cold flow/creep. However, they are still recommended for mild or low-pressure application.

Viton Gasket vs Task-Line®

Gasket Material Viton
Viton Gasket
Other Gasket versus Task-Line® Gasket

Task-Line® PTFE Gasket
Task-Line® PTFE Gasket

Task-Line® has a better versatility as it can cope with more chemicals than Viton gasket. However, PTFE and Viton are used for different application, it is recommended to check our chemical resistance chart here prior to using the gaskets.

Rubber/Plastic Gasket vs Task-Line®

Gasket made from rubber material
Rubber Gasket
Other Gasket versus Task-Line® Gasket

Task-Line® PTFE Gasket
Task-Line® PTFE Gasket

Rubber/Plastic is only applicable for mild application due to its low chemical resistance. Task-Line®, however, is far more superior than rubber/plastic gasket as it can handle aggressive chemicals such as chloride and sulphate acid.

Final Words

If you are interested in using Task-Line® gasket for any of your projects, they are available from size ½” to 6” in either 150# or 300# ANSI rating. We also offer the thickness of 1/8” or 3/32” (other thickness is available upon request). If you would like to find out more information, please contact us at enquiry@wahjooseng.com or (65) 62983211 for any enquiries.

Visit our website to see other hoses and couplings here.