Note: To print this bulletin on ammonia service, please click here.

Feeding the World’s Population

Between 1900 and 2000, the world’s population grew from 1.6 billion to 6 billion. Today, it registers at 7.9 billion.[1] Something happened in the 20th century that allowed this great explosion of population to take place.

While a mix of inputs are required for plant growth, nitrogen is considered the most important given how much is required. As such, crop yields are limited by the amount of nitrogen available and farmers in centuries past relied upon manure to augment the work of nitrogen-fixing bacteria in the soil to deliver this critical element.

In the early 1900s, a pair of German chemists discovered how to synthesize ammonia (NH₃)–a nitrogen-hydrogen compound–and thereby boost the amount of nitrogen available to plants. Inorganic nitrogen fertilizers, often injected into the soil as liquid ammonia, allowed for great increases in crop yield, the kind of increases that could spur a population explosion.

Given the role it plays in feeding the world’s population, ammonia is one of the most widely produced chemicals. One hundred and eighty million metric tons are produced annually.[2] With the world’s largest population, it may come as no surprise that China is the top producer. India, Russia and the United States follow.[3]

Ammonia is also used in commercial refrigeration systems and in household cleaners, and its use as a potential hydrogen fuel source is a popular topic of conversation as well

Ammonia as a Health Hazard

Direct exposure to ammonia in high concentrations is hazardous to human health and numerous government agencies and industry associations have developed various specifications, procedures and training sessions to limit leaks. These efforts, along with correct handling and preventive maintenance, have kept incidences of leaks and human injury to relatively low levels.

Interestingly, Fertilizer Grade Ammonium Nitrate is listed as a chemical of interest in the U.S. Department of Homeland Security’s Chemical Facility Anti-Terrorism Standards.[4] While this signals the potential for its use as a chemical weapon, for the purposes of this bulletin, it underscores the importance of safety in the design and operation of ammonia piping and transfer systems.

Metal Hose in Ammonia Service

Common applications for hoses in these systems include connections between fixed loading and unloading systems, and in nurse tank trailer, rail and truck transport. Metal is often the preferred material of construction given its chemical compatibility. Metal hoses also offer a more robust design given braid layers protect the inner core from abrasion and welding is the end fitting attachment method.

The 300 Series stainless steels are suitable options for most ammonia service applications, including those involving anhydrous ammonia, a liquid solution that is used both as fertilizer and commercial refrigerant. Anhydrous ammonia corrodes copper and zinc alloys and can also attack rubber and certain plastics.

A gas at room temperature, anhydrous ammonia is cooled to its liquid state before being transported under pressure to its destination. When working with anhydrous ammonia gas at elevated temperatures, the 300 Series stainless steels are not recommended. Contact the factory for details about other options.

When working with ammonium bromide, ammonium sulfate or ammonium chloride in concentrations above 10%, 316L is recommended above 304 and 321 which are only partially resistant to these media.

For a more complete listing of alloy compatibility with ammonia have a look at our corrosion resistance chart.

Concerns Around Explosiveness

While ammonia is non-flammable, it can ignite in the presence of certain compounds, namely halogens, with explosive force. Chlorine and various chlorides are halogens, so great care must be taken to remove contaminants during production and to avoid their entry into the system during shipment, storage and installation.

Key precautions must be taken during manufacturing, and include removing any chips or debris from the inside of the hose after cutting and purging welds with argon gas. Welds and welders should be certified under ASME Section IX, the industry standard for quality welding.

Considerations on Stress Corrosion Cracking

In addition to being a potential ignition source, contaminants also exacerbate corrosion in a hose. With its strong affinity for water, it is important to prevent an influx of moisture into an ammonia piping system.

Chloride contamination from the ingress of water can reduce the service life given material sensitivity to these compounds. Stainless steel and chlorides are a pairing highly susceptible to stress corrosion cracking (SCC). This form of corrosion occurs at the intersection of a susceptible material, working or residual stress experienced above the SCC threshold, and a corrosive environment. Cracks may lead to leaks if not identified soon enough.

Regular inspection of hoses in ammonia service is important for identifying cracks, as well as damaged braid, deformation of the hose, cracked fittings, or traces of media on or around piping components that could indicate imminent failure.

For further questions, please contact us.

Footnotes

[1] United States Census Bureau. U.S. and World Population Clock. Retrieved August 11, 2022 from https://www.census.gov/popclock/

[2] Alexander Tullo. 8 March 2021. Chemical & Engineering News. Is ammonia the fuel of the future?. Retrieved August 11, 2022 from https://cen.acs.org/business/petrochemicals/ammonia-fuel-future/99/i8

[3] Johnny Wood. 29 October 2021. Forbes. Scaling Ammonia Production For The World’s Food Supply. Retrieved August 11, 2022 from https://www.forbes.com/sites/mitsubishiheavyindustries/2021/10/29/scaling-ammonia-production-for-the-worlds-food-supply/

[4] Cybersecurity & Infrastructure Security Agency. Chemical Facility Anti-Terrorism Standards (CFATS). Retrieved August 11, 2022 from https://www.cisa.gov/chemical-facility-anti-terrorism-standards.

Note: To print this bulletin on how much weight a hose hung vertically can support, please click here.

Hoses are sometimes hung vertically. Oftentimes, it’s for a temporary application and, typically, it’s a large bore hose that’s being used. In these situations, a user may wonder how long the hose can be before the combination of its own weight and the weight of media flowing through it become too much.

The long and the short of it is it’s unlikely that there would be an issue.

Finding the Impact on Pressure Ratings

Braided hoses are designed to resist internal pressure as noted by their pressure ratings, and when a hose hangs vertically, some of the pressure carrying capacity does get “used up.”

What gets “used up” is determined by the weight of the hose, braid, end fittings, and flow media. Totaling these forces, converting the sum into units of pressure, and subtracting the result from catalog ratings will give you the updated pressure limits.

Example Using Penflex Single Braided 10” 700 Series

Let’s say we are using a 10” x 12’ hose to direct water from a container above into a pit below. The assembly has a slip-on flange at each end. We calculate the weight of the hose, braid and end fittings as follows.

To determine the weight of flow media, multiply the hose’s total volume by media density. Penflex’s 716-1SB-160 has a volume per foot of 1018.96 in³. In a 12’ run, the total volume will be 12,227.52 in³.

To convert force to pressure, divide by the net effective area. This is the area of the hose using the radius which comes from the average of the inner and outer diameters. The ID of 716-160 is 9.82” and its OD is 11.18.” Using the formula below, we find the effective net area is 86.56 in2.

E = ((I +O)/4)² x p
E = 27.56 x p
E = 86.59 in²

Then, to finish the conversion, divide total weight by net effective area.

Pressure = 754.9 lbs./86.59 in²
Pressure = 8.72 PSI

716-1SB-160 has a MAWP of 230 PSI. Just 8.72 PSI will be “used up” when this hose hangs vertically. As mentioned earlier, unless the operating pressures are close to the MAWP, or hose lengths are quite long, a hose hung vertically will not see any meaningful reduction in pressure ratings.

For further questions, please contact us.

Note: To print this bulletin, please click here.

Knowing how long a metal hose will last in service would make life easier. We could more accurately plan purchases for replacement parts and then schedule time to install those parts, all while reducing the likelihood of failures.

While this isn’t a pipe dream—some companies have successfully determined average service life for hoses in specific applications through careful observation and record-keeping—it is unrealistic to expect that an answer can be given without such attention to data collection and the monitoring of outcomes.

Any information that could be given at the manufacturer’s level would reflect how hoses behave in certain testing circumstances. We know that the same hose will last longer if pressure is reduced or bend radius is increased, and—conversely—that service life will be shorter if pressure increases or bend radius decreases.

It is impossible to test every possibility. And of course, we are only talking about two given variables that impact service life. Whether a hose is installed properly is another, and there are many more.

Retesting to Reaffirm Service Life

Some refineries and chemical plants look to their suppliers to retest hoses to ascertain whether they are “still good.” Such a process can give users a false sense of certainty, mistaking a hose that has been successfully retested as one that will last for another, often unspecified, stint in service.

This is misguided.

While pressure testing can be used to determine the continuing strength of a hose, it will not predict its remaining life span. We have seen retested hoses put back in service only to fail a week later.

Passing such a test does not negate the unknown impact of exposure to corrosive media, harsh environments, bending, twisting, intermittent flow, vibration, and improper handling. With this in mind, a retesting agency should not be responsible for how much longer a hose will last in service.

When to Take a Hose out of Service

Without data on how a hose operates under certain circumstances—which can only be collected by the end user—we cannot accurately predict how long a hose will last. The challenge then becomes when to take a hose out of service to avoid premature failures. And there’s no exact science to it.

We recommend regular inspections using a checklist to help maintenance personnel identify potential problems. If any of the indicators are observed, replacements should be considered. Keeping track of observations, and how long each hose lasts in every application, will, overtime, yield the kind of data that will allow users to predict service life for hoses in their facility.

Here’s Janet Ellison, our director of quality and engineering, to talk about the points highlighted in this bulletin.

Note: To print this bulletin, please click here.

The information below on how to install an expansion joint comes from the Standards of the Expansion Joint Manufacturers Association 10th Edition.

Metal bellows expansion joints have been designed to absorb a specified amount of movement by flexing of the thin-gauge convolutions. If proper care is not taken during installation, it may reduce the cycle life and the pressure capacity of the expansion joints which could result in an early failure of the bellows element or damage the piping system. 

The following recommendations are included to avoid the most common errors that occur during installation. When in doubt about an installation procedure, contact the manufacturer for clarification before attempting to install the expansion joint. The manufacturer’s warranty may be void if improper installation procedures have been used. 

Do

1. Inspect for damages during shipment, i.e., dents, broken hardware, water marks on carton, etc.
2. Store in clean dry area where it will not be exposed to heavy traffic or damaging environment.
3. Use only designated lifting lugs.
4. Make the piping systems fit the expansion joint. By stretching, compressing, or offsetting the joint to fit the piping, it may be overstressed when the system is in service.
5. It is good practice to leave one flange loose until the expansion joint has been fitted into position. Make necessary adjustment of loose flange before welding. Install joint with arrow pointing in the direction of flow. Install single Van Stone liners pointing in the direction of flow. Be sure to install a gasket between the liner and Van Stone flange as well as between the mating flange and liner.
6. With telescoping Van Stone liners, install the smallest I.D. liner pointing in the direction of flow.
7. Remove all shipping devices after the installation is complete and before any pressure test of the fully installed system.
8. Remove any foreign material that may have become lodged between the convolutions.
9. Refer to EJMA Standards for proper guide spacing and anchor recommended

Don’t

1. Do not drop or strike carton.
2. Do not remove shipping bars until installation is complete.
3. Do not remove any moisture-absorbing desiccant bags or protective coatings until ready for installation.
4. Do not use hanger lugs as lifting lugs without approval of manufacturer.
5. Do not use chains or any lifting device directly on the bellows or bellows cover.
6. Do not allow weld splatter to hit unprotected bellows. Protect with wet chloride-free insulation.
7. Do not use cleaning agents that contain chlorides.
8. Do not use steel wool or wire brushes on bellows.
9. Do not force-rotate one end of an expansion joint for alignment of bolt holes. Ordinary bellows are not capable of absorbing torque.
10. Do not hydrostatic pressure test or evacuate the system before installation of all guides and anchors.
11. Pipe hangers are not adequate guides.
12. Do not exceed a pressure test of 1 1/2 times the rated working pressure of the expansion joint.
13. Do not use shipping bars to retain thrust if tested prior to installation.

When dealing with expansion joints, do not remove shipping bars until installation is complete.

To print this bulletin, please click here.

The 300 series austenitic stainless steels are a set of iron-based chromium-nickel alloys designed to resist corrosion. This in combination with excellent formability, resistance to wear, and strength at temperature make them common materials of construction within piping systems.

Differences between the alloys are slight but deliberate. While they can be used interchangeably in many applications, sometimes there is an ideal solution. Substitutions in such situations could mean compromised service life.

Corrosion Resistance

As corrosion resistance is one of the primary reasons end users opt for metal hose, application media typically guides alloy selection. 304 is often used as it is the most cost-effective option, though 321, and 316 especially, offer better corrosion resistance. For this reason, most Penflex hoses are made using 321 or 316L.

Braid is usually 304L as it will not be in contact with flow media, though 316L is an option if the application is in a corrosive environment—like in, on or near the ocean—or if the outside of the hose will be subject to corrosive media via drips, spray, run-off, etc.

For especially corrosive applications, superior corrosion resistant properties can be found among higher-nickel alloys like Monel® 400 and Hastelloy® C276.

300 Series Stainless Steels: Chemical Composition

The chart below shows the chemical composition of the most common 300 series stainless steels used in the metal hose industry. Single figures signify the maximum percentage allowable under ASTM 240 requirements.

304 is considered the baseline when it comes to corrosion resistance. Various alloying components have been added to the 321 and 316 grades to increase corrosion resistance.

In the case of 304L and 316L, carbon has been taken out. The “L” stands for “low carbon.” Lower carbon alloys are less susceptible to carbide precipitation in the Heat Affected Zone (HAZ) than their standard type counterparts.

Chromium and carbon can mix under the heat of welding to create chromium carbides at the grain boundaries. This reaction depletes the chromium layer that gives stainless steel its corrosion resistant properties, ultimately making the HAZ a target for chemical attack. One way to combat carbide precipitation is to reduce the amount of carbon in the parent material.

Another more effective way is to add titanium to the metal, as is the case with 321. With Type 321, rather than being attracted to the chromium, carbon is attracted to the titanium. This helps ensure the passive chromium layer remains intact.

With both 316L and 321, post-weld cleaning processes can eliminate corrosion due to residual carbide precipitation.

Resistance to Pitting Corrosion

Molybdenum is added to the 316 grades to increase resistance to pitting corrosion, especially in the presence of chlorides. To help in the selection of an appropriate alloy, an equation based on chemical composition was developed. PREN, or the pitting resistance equivalent number, is a theoretical way of comparing pitting corrosion resistance among various alloys.

Taking precautions to ensure the HAZ more closely resembles parent materials in terms of corrosion resistance and planning for pitting corrosion is important if corrosion resistance is a priority. In applications where corrosion is not an issue, any of the 300 series alloys will likely deliver similar results.

Rates of Corrosion Among 300 Series Stainless Steels

Another way to demonstrate differing levels of corrosion resistance among these alloys is to consider expected rates of corrosion. Rates vary from chemical to chemical and are illustrated in Penflex’s corrosion resistance chart. In thinking about how much metal will be worn away each year, the difference between corrosion resistance capabilities can be seen more easily.

And when it comes to corrosion resistance, it’s not just the alloy that must be considered, but the wall thickness of the alloy as well. We’ve pulled together another bulletin to specifically address this topic.

Derating Factors at Elevated Temperatures

No other materials can maintain their properties through such a wide temperature differential as metal. Anything below 0°F will likely require metal so cryogenic applications are a common use case for metal hose. Some of the austenitic stainless steel mechanical properties actually increase at low temperatures! Anything above about 400°F will also require metal so applications with super saturated steam or those within steel mills or furnaces are also likely scenarios for metal hose.

It’s important to remember that with increased temperatures comes a reduction in pressure ratings, and there are some differences in those factors among the common 300 series stainless steels. Derating factors are based on braid alloy.

The temperature reduction factors for 321 and 304 are higher than 316 until about 700°F and then the reverse is true with 316 having the higher reduction factors than 321 and 304. The higher the derating factor, the higher the pressure ratings will remain.

For example, to calculate the maximum working pressure for a P4 Series ¾” 321 stainless steel corrugated hose with one layer of 304L braid that will be operating at 800°F, multiply working pressure (940 PSIG) by appropriate derating factor (.73).

The working pressure for the hose at 800°F is 686 PSIG.

Penflex developed its derating factors after gathering raw data on tensile strength at elevated temperatures from major material suppliers and taking the lowest values in each category for the various alloys. For this reason, they may be more conservative than derating factors published by NAHAD or ISO 10380.

It’s important to remember the maximum working temperature of the end fittings and their method of attachment also needs to be considered when working with increased operating temperatures.

For application temperatures above 1000°F, we often suggest Inconel® 625.

Considering the Entire Application

As mentioned above, in many applications substitutions in hose alloy will have little impact on hose performance. However, when temperatures rise, pressures increase, or hoses cycle frequently, we must pay closer attention.

The impacts of temperature, pressure and movement can be compounded leading to corrosion sooner than anticipated had application media been the only factor in our corrosion calculations. While the differences between the 300 series stainless steels may seem small, we can begin to see how quickly they could become magnified.

Please contact us with any questions.

To print this bulletin, please click here.

The braid on a metal hose must be kept in tension if it is to play its role as pressure carrier well. Without it, under pressure, a hose will grow back into a tube.

Compress a hose axially, and the braid will fall out of tension. Therefore, we do not use braided hoses to absorb axial movement. (A hose can absorb axial movement in a piping system if it is hung in a loop. In this configuration, the hose does not move axially though.) Fail to capture all braid wires in a cap pass, and those wires left out are no longer, or rather, never were, in tension.

Pressure ratings depend on all braid wires remaining in tension during operation. Theoretically, every wire carries an equal portion of the pressure and a few loose wires can reduce a braid’s pressure capacity below the intended working pressure.

The Cap Weld

Cap pass welds connect a hose and braid. They precede any fitting attachment welds and are judged based on several criteria, whether all braid wires are captured chief among them.

Beyond a reduction in pressure ratings, once wires pull out from the cap pass, the area of the hose just behind it becomes more susceptible. If any cycling or bending is taking place, fatigue will set in sooner, resulting in premature cracks and, eventually, failure.

The image below offers an example of braid wires that were not captured in the cap pass. In this instance, given the number of wires and their uniform geometry, it is likely significant sections of the braid slipped below the top of the ferrule during the welding process, never even coming into contact with the puddle spanning hose to ferrule.

If only a few wires were missed, localized stress at the end fitting caused by mechanical bending, vibration or other application forces could have contributed to pulled out wires.

Approaches to Welding the Cap Pass

Aside from skilled welding technique, the best way to ensure all braid wires are captured is to pull the braid 1/16” above the ferrule before welding.

Keeping the braid flush with the hose may make for easier welding, but the likelihood of failing to capture all braid wires offsets any potential gains in time saved by taking this approach.

Capturing every braid wire is not the only consideration for a good cap weld. A common approach, known as the burn down method, accomplishes this goal but fails to take into account two important details.

First, this weld cannot be purged and therefore ignores the metallurgical effects of welding. (For more information about argon purging, and its role in delivering high quality welds, have a look at this bulletin).

Second, the uneven geometry reduces the attachment weld flexibility and special care must be taken to ensure proper joint fit-up. This is important to ensure joint strength and quality.

Penflex’s method eliminates these issues and accomplishes the goal of capturing the braid wires while allowing for purging and creating an easy geometry for the attachment weld.

The Cap Pass Gold Standard

Here’s a look at a well-executed cap pass. In the first image, the ferrule has been removed, and looking at the braid from the outside, we can see there are no loose wires. In the second image, a close trim cross-section of the wire in the cap pass shows that 100% of the wires were captured.

Penflex Welder Training

Cap passes of this caliber are consistently achievable, with proper training. Penflex offers a one-week ASME Section IX-certified program for welders with mid-level experience. The training is designed to improve technique, and perfecting cap pass welds is one of the skills achieved through the training.

For more information about our Welder Training Program, please click here.

To print this bulletin, please click here.

Oftentimes engineers use metal bellows to damp vibrations in a piping system. While they protect surrounding pipes and equipment from damage, bellows themselves are not impervious to damage.

Work hardening occurs with each cycle and, as a result, the bellows become increasingly brittle over time. The more brittle an expansion joint becomes, the higher the likelihood of stress cracking—seen within the valley or at the crest of a convolution—and subsequent failure.

In rare cases, resonance can cause near immediate failure. Given the challenges associated with vibration, it’s a good idea to have a conversation with a Penflex sales engineer when designing components for these kinds of applications.

Applications Where Vibration is a Concern

The most common high vibration scenarios include exhaust and pump system applications.

High flow velocity can also lead to damaging vibration, though engineers take a different approach when designing bellows for applications where this is a concern.

Designing Metal Bellows with High Vibration in Mind

A flexible, 5-ply design with a low spring rate is the “gold standard” for high-vibration applications.

Flexibility is a key characteristic as flexible bellows are slower to work harden. In delaying the onset of embrittlement, we can also delay the advent of stress cracking and thus prolong service life.

Stresses are distributed across the bellows in a multi-ply expansion joint. This also slows work hardening. And while many variables contribute to flexibility, adding plies helps to make an expansion joint more flexible as well. Finally, where pressure is a concern, the multi-ply design delivers a robust wall thickness to accommodate higher working pressures.

Low spring rates are desirable as they will keep the forces exerted on pumps by expansion joints low.

When high flow velocity is a concern, Penflex uses the EJMA guidelines for liners. Based on different flow velocities and diameters, the guidelines offer recommendations for smoothing media flow within an expansion joint.

Inconel® 625 LCF

Another consideration for expansion joints in high-vibration application is the material of construction. Inconel® 625 LCF was specifically designed for the metal bellows industry. LCF stands for “low cycle fatigue.”

It is an excellent choice for high-vibration applications due to its better thermal fatigue resistance and better cycle fatigue properties when compared to other, similar alloys.

Vibration Analysis

Penflex sales engineers can confirm an expansion joint will not operate within the resonant range, assuming system frequencies are known.

Work hardening and subsequent stress cracking is a common cause of expansion joint failure, but one that can be avoided through thoughtful bellows design. For more information, please contact us.

To print this bulletin, please click here.

Vibration is common in many piping systems. However, once it becomes a defining characteristic of the application it is safe to assume that vibration poses some very real risks to system integrity.

Deciding whether an application is “high vibration” is mostly a matter of opinion. Ascertaining amplitude without the use of sophisticated measuring equipment is difficult. Even if vibration could be quantified, design codes offer little in the way of defined limits.

Indications of Vibration Induced Failure

Circumferential cracks, typically on the crest but also in the valley of the corrugation, are symptomatic of vibration fatigue.

So too is braid wear. Braid wear is indicative of significant movement of the braid relative to the hose, like what you might expect to see in high vibration applications. The tensile strength of the braid wires is higher than that of the hose, so the hose loses material first.

In essence, the braid wires “saw” into the hose, creating divots as seen below.

It’s important to note these indicators are not exclusive to vibration fatigue. Cracks can be a sign of torsion while braid wear can also result from mishandling. However, if a hose has failed due to vibration, it is likely that cracks or braid wear will be visible upon inspection.

Causes of Excessive Vibration in Piping Systems

Mechanical vibrations from pumps or moving equipment attached to the hose can induce movements that create premature ware and early failures.

Another kind of vibration is “flow induced,” generally caused by high flow velocity inside the hose. The rule of thumb for maximum recommended flow velocity in a straight run of braided hose is 150 ft/sec for gas and 75 ft/sec for liquids.

Considerations for High Vibration Applications

There are no hard-and-fast rules when it comes to vibration. As a result, one can only attack the problem through trial and error.

When vibration failures occur, the typical response is to change the mass or stiffness of the assembly. Sometimes a combination of the two will yield a better result. Adding components such as external bend restrictors, additional braids and internal flow liners or increasing wall thickness can all be inexpensive fixes to overcome premature vibration failures.

Flexibility is another important consideration in high vibration applications, and there are some requirements as to minimum live length of a hose assembly in such scenarios. Those requirements can be found in this table here.

For assistance with flexible piping components in high vibration applications, contact us at sales@penflex.com.

In the video below, Penflex Director of Quality and Engineering Janet Ellison discusses how to approach installing hoses in high vibration applications.

To print this bulletin, please click here.

Robust lance hoses are needed to deliver oxygen to a Basic Oxygen Furnace (BOF). The heat of the surrounding environment, the frequent handling—and mishandling—of the hoses, and the need to maintain strict cleanliness present a set of challenges for engineers and maintenance personnel.

There are various options when it comes to lance hose design. One of the biggest decisions to make revolves around what material to use for the inner hose, whether to opt for metal or rubber.

In either design, layers of braid or insulation and metal armor complete the hose assembly.

Working Temperatures

Metal has a higher maximum working temperature than rubber. Rubber hoses require insulation to reach working temperatures of 1000 °F while the 300 Series austenitic stainless steels can handle temperatures up to 1500°F. Exotic alloys such as Inconel 625 can accommodate even higher temperatures.

It’s often the ambient heat that engineers must keep in mind when designing components for steel mills, but this can vary greatly depending upon proximity to furnaces and other pieces of equipment.

Hose Flexibility

As lance hoses move in and out of the furnace, flexibility is a desired characteristic. Rubber hoses are often more flexible than metal hoses in smaller diameters, but that difference decreases or becomes negligible as hose size increased.

Lances are typically six, eight or ten inches in diameter, fitting into this second category where neither metal nor rubber have a definitive edge in terms of flexibility.

Lightweight Lance Hoses

Despite having a heavy wall construction, metal hose assemblies weigh significantly less than rubber hose assemblies. The increased weight of the latter, which is about 1.5 – 2 times more, can be difficult to handle and put a lot of stress on the piping system.

Complete rubber hose assemblies used for oxygen lancing are generally far more expensive than a metal hose assembly and, given life span ends of being the same, one wonders whether the increased price justifies an arguable marginal increase in flexibility. And a heavier, harder to handle flexible hose at that.

For more information about Penflex’s metal oxygen lance hose assemblies, take a look at this handout.

Note: To print this bulletin, please click here.