Didier Vassal, Vice President OEM and Maritime Services at Victaulic, compares the flanged and grooved pipe-joining methodologies and explains the advantages that grooved pipe joints provide over flanges.
Efficient piping systems are essential for the range of services needed on board a vessel including secondary systems such as bilge and ballast systems, sea and fresh water cooling, lube oil, fire protection and deck wash.
For these systems, where piping class permits, an effective pipe-joining alternative to welding/flanging is the use of grooved mechanical joints which offer a range of technical, economic and practical benefits. These include enhanced performance; faster, simpler installation and maintenance and weight reduction on board.
In a flanged pipe joint, two mating flanges are bolted together and compress a gasket to create a seal. As the bolts and nuts of a flanged joint absorb and compensate for system forces, over time the bolts and nuts can stretch and lose their original tightness due to pressure surges, system working pressure, vibration and thermal expansion and contraction. When these bolts experience torque relaxation, the gasket will lose its compressive seal, which can result in varying degrees of leakage.
Depending on the location and function of the piping system, leaks can be costly and hazardous, resulting in maintenance/repair downtime and exposure to risk. Gasket replacement will be required when the joint is taken apart, as the gasket will bond to the flange faces during the course of time. When the joint is disassembled, the gasket will need to be scraped from both flange faces and these surfaces will need to be cleaned before the gasket is replaced, again increasing maintenance downtime. Due to the bolting forces along with system expansion and contraction, flange gaskets can also develop compression “set” over time, presenting another cause of leakage.
The design of a grooved mechanical pipe joint overcomes these performance issues. A groove is first formed in the pipe end and the piping connection is secured by a coupling which houses a resilient, pressure-responsive elastomer gasket. The coupling housing fully encloses the gasket, reinforcing the seal and securing it in position as the coupling engages and forms a positive interlock into the pipe groove. The latest coupling technology enables pipes up to 24” (600mm) in diameter to be fully assembled with only two nuts and bolts in order to secure the self-restraining joint. The mechanical joint creates a triple seal due to the design relationship between the pipe, gasket and housings, which is enhanced when the system is pressurized.
Rigid and Flexible Couplings
Available in both rigid and flexible forms, grooved mechanical pipe couplings are Class Society Type Approved, and may be used in lieu of welded/flanged methods in 30 systems, subject to installation criteria established by each certifying agency.
Rigid couplings are used, for example, around areas such as manifolds and valves, where they offer easier access and replacement than flanges. By nature of their design, rigid couplings also provide axial and radial rigidity comparable to flanged or welded joints.
Flexible couplings have advantages in applications where relative movement between the pipe and supporting structure is anticipated, in addition to pipe movement resulting from thermal expansion or vibration. Expansion and contraction can stress the flange and piping, which can compromise the gasket over time. When this occurs, the joint is at risk of leaking. Grooved flexible couplings can accommodate pipe displacement in the form of axial movement or angular deflection. For this reason they are ideal for installing long piping runs especially between blocks where high seas can cause flanges to loosen over time, resulting in leaks and the risk of pipe separation. Both rigid and flexible couplings also provide the benefit of noise and vibration attenuation, eliminating the need for specialised noise reduction components and perishable rubber bellows or similar items.
Using a mechanical grooved piping system can speed up and simplify both installation and maintenance and improve the efficiency of onboard piping systems.
Ease of Installation
On initial installation, bolt holes of a flange must be precisely aligned and then tightened to hold the joint. The bolt-hole index on equipment inlets and outlets must also line up perfectly with the flange on the piping to be connected to the unit. With only one of a number of fixed positions determined by the number of holes in a flange, a fitting or valve can only be rotated to match the bolt holes. Additionally, the opposite end of the flanged pipe must also line up with its mating flange, which further increases assembly difficulty and the risk of misalignment.
Grooved piping systems do not have this problem and allow much more convenient installation with a full 360-degree rotation available for the pipe and mating components. There is no bolt-hole pattern to line up, and a coupling can be oriented at any position around the joint. The coupling can be rotated around the pipe to provide easy access to the bolts and simplify access to the equipment.
In addition to eliminating misalignment during installation, a coupling’s 360-degree orientation capabilities, together with its smaller profile compared to a flange, make the installation of grooved systems ideal for confined spaces.
Additionally, the installer can orient all of the assembly bolts on each joint in the same position to ease system inspection and maintenance.
Flanges are roughly twice the outside diameter of the pipe they are attached to. On average, grooved couplings are only half this size. The size advantage of the smaller design makes the grooved system ideal for jobs where space is limited, such as deck and wall penetrations - a fact recognised as far back as the 1930s when Victaulic couplings were originally used in U.K. shipyards.
Speed of Assembly
Because couplings have fewer bolts and no torque requirements up to 12” (300mm), grooved piping is much faster to install than flanging. Unlike flanges that must be welded to the pipe end, grooved valve assemblies do not require welding, which further cuts installation time and eliminates potential heat damage to the valve while also reducing safety risks by eliminating hot works.
A comparison of a DIN 150 ballast line installed using Victaulic grooved products versus traditional joining methods showed a 66% reduction in total installation time required (150.47 man hours vs. 443.16 man hours). The time needed to install 52 slip-on flanges and weld elbows and tees compared with 60 rigid couplings showed the largest time differences.
Couplings require just two bolts up to 24” (600mm) pipe size. For comparison, at the higher size range a flange would require a minimum of 20 sets of nuts and bolts.
In addition, flanges require time-consuming star pattern tightening with specialised wrenches to measure and ensure that correct torque specifications are achieved. Grooved pipe technology allows couplings to be assembled using standard hand tools and the joint is properly installed once the mating bolt pads of the coupling housings meet metal-to-metal. A simple visual inspection confirms correct assembly. Flanges, on the other hand, do not provide visual confirmation: the only measure to ensure proper assembly is to fill and pressurise the system, check for leaks and retighten the joints as needed.
The same characteristics of grooved piping systems that accelerate installation—fewer bolts and no torque requirements — also make system maintenance or alteration a quick and simple task. To gain access to a pump or valve, for example, the two bolts of the coupling are loosened, and the housings and gasket are removed from the joint. In a flanged system, multiple bolts need to be removed. The same time-consuming bolt-tightening sequence required upon initial installation is also required upon reassembly of the flange.
Because they do not require retightening, couplings eliminate much of the routine maintenance associated with flanges. Unlike a flange that puts variable stress on the gasket, nuts and bolts, a coupling holds the gasket in precise compression from the outside of the pipe joint. Additionally, since coupling gaskets are not subjected to high compressive forces, they do not need to be replaced on a regular maintenance schedule, while flange gaskets need to be replaced when the system is disassembled for maintenance.
To attenuate system noise and vibration, flanged systems require rubber bellows or braided flexible hoses. These items can fail due to overextension and, with normal wear, need to be replaced every 10 years on average, incurring cost and system downtime. Mechanical grooved pipe couplings, however, last the life of the system. Their ability to accommodate system vibration reduces the risk of joint failure, without the need for speciality products that require periodic repair or replacement. The resilient elastomeric gasket contained within both flexible and rigid couplings is very durable and can handle significant operating pressures and cyclical loading. A system can be pressurized and depressurized repeatedly without fatiguing the elastomer gasket.
Valve assemblies are typically constructed with flanged components. However, this joining method can add unnecessary weight to a piping system. A 6” (150mm) flanged valve assembly constructed with a lug butterfly valve, connected with weld-neck flanges and eight bolts and nuts on each side of the valve, weighs approximately 85 lbs. A 6” (150mm) valve assembly that utilizes a grooved-end butterfly valve, grooved-end pipe and two rigid couplings to connect the components weighs approximately 35 lbs, representing a 58% weight reduction over the flanged assembly. A grooved valve assembly is therefore, an ideal alternative for the shipbuilding industry.
The above-mentioned comparison of a DIN 150 ballast line installed showed a weight reduction of 30 percent (2,164 lbs vs. 3,115 lbs) when Victaulic grooved products were used instead of traditional joining methods. The 52 slip-on flanges, bolt sets and gaskets, versus 60 rigid couplings accounted for major weight increases in the welded/flanged system.
Weight reductions by using grooved pipe couplings instead of flanges are achievable across a range of pipe sizes. The magnitude of the reduction depends on the pipe diameter and type of coupling used. In tests where piping was connected using one Victaulic Style 77 coupling – the heaviest coupling in the range – compared with two light-weight PN10 slip-on flanges the total installed weight of the grooved assemblies was significantly lower. Weight reductions were recorded as follows: 4” (100mm) – 67 percent; 12” (300mm) - 54 percent; 20” (500mm) – 60.5 percent.
With the lighter-weight flexible Style 75 or rigid Style 07 couplings and/or a heavier type of flange, weight reductions of 70% are easily achievable. As an example, a 24” (600mm) flanged set for a TG2 system would weigh 507 lbs but a comparable assembly using Victaulic couplings would weigh only 88 lbs. Shipyards that have used grooved couplings in preference to flanges on selected systems have recorded weight savings of 12 tons on offshore support vessels and 44 tons on cruise ships.
The economic benefits of grooved technology to ship owners are clear: less weight means more cargo or passengers and less fuel consumption. It makes the handling of piping systems on board easier as well.
Grooved piping systems can offer significant advantages over their flanged equivalents because of their speed of installation, maintainability and reduced weight. These characteristics, coupled with additional benefits such as reliability, ease of alignment and lower safety risks, are leading owners, engineers and shipyards to choose grooved mechanical systems instead of flanges.
This growing trend towards the use of grooved technology is supported by suppliers of equipment such as heat exchangers, box coolers and chillers, along with valve and compressor manufacturers, many of whom are now providing their products with grooved end connections. The range of services where grooved pipe couplings may be used is steadily increasing. Building on successful applications in water systems, Victaulic is continuing its long history of innovation to develop fire-resistant gaskets and gain Type Approval for their use on maritime fuel services.
(As published in the April 2014 edition of Maritime Reporter & Engineering News - http://magazines.marinelink.com/Magazines/MaritimeReporter)
field installation and increased flexibility. A large selection of springs is available to handle a wide range of applications and pressure drops. Seat tightness is precision engineered to provide the same low leakage characteristics as single seated, unbalanced valve designs. The bonnet gasket is spiral
compressed asbestos gaskets. Positive seating is achieved with no metal-to-metal contact to cause friction and wear. The flow in the piping is sealed tight on both sides with an open space in between. "To inspect for leakage," explained Mr. Daniels, "you just take a quick glance into the open space
Victaulic developed a new nitrile gasket for the maritime industry: the Grade T “Type A” gasket, designed for use with specific Victaulic couplings and flange adapters, and designed to simplify gasket specification and offers superior fire-resistant performance. The nitrile Grade T Type A gasket can be
to both sides of the penetration, also cures to a rubber-like mass that withstands tremendous pressures, enabling it to achieve its gas and watertight ratings. Milcom selected the RISE system for several reasons. "First and foremost, I'm confident that RISE offers the best fire-stop protection
tanker and shoreside service. The valves handle high-pressure drops in either throttling or on/off service and will maintain flow characteristic and tight shut-off and start-up through cool-down and defrost. Other key features include: positive guiding, for accurate control and reduced trim wear
—Literature Available According to Clemco Industries, Burlingame, Calif., the Clemlite™ system of abrasive blast hoses, couplings and nozzles can heighten productivity by lightening operators' loads by as much as 62 percent, while offering improved safety and economy. Combining ultra-light weight wi
Victaulic, a manufacturer of mechanical pipe joining systems, introduces Vic-Press, an IACS-approved flame-free press system for joining small-diameter stainless steel pipe. With Type Approval certification from IACS member agency Germanischer Lloyd, Vic-Press offers a quick, simple, safe and reliable means
Jim Scott, who was instrumental in the development of the conical seal in the 1950s, founded Seco Seals, Inc. in 1969 to fill the need for conical seals for 37 degree flared tube fittings. Since then, the company has become the standard for 37 degree flared tube fitting seals for every application, from
An energy-saving device that replaced steam traps on U.S. Navy ships won a $25,000 prize for the inventor, a civilian employee of the Navy, at a ceremony on the White House lawn. President Carter made the presentation to Lawrence L. Guzick for a constant flow Drain Orifice that is saving the U.S.
, access hatches allow easy repair or replacement of the propulsion units Vertically layered rubber fenders grip a steel hull like fingers, maintaining tight control yet easy disengagement with very little abrasion Two GM Detroit Diesel 16V-71N engines generate 1,070 hp, and are splayed 15 degrees off
use pressure resistant materials such as thermoplastic rubbers to add buoyancy Fiber optics are processed in several different configurations including tight buffered constructions reinforced with aramid fiber and fiber optics encapsulated inside hermetically sealed stainless tubes. Both the plastic and
MR Products & Services www.MaritimeEquipment.com Industrial Grade Pressure Washers MARINE FENDER & DOCK SYSTEMS RUBBER FENDERS ~ PANEL FENDERS ANCHORS ~ CHAIN ~ PELICAN HOOKS ABSORBENTS ~ DREDGE PIPE FLOATS UNDERWATER LIFT & SALVAGE BAGS D-SHAPE, WING & TUGBOAT
to if it will not. It uses the sensors on the gency. level of danger the vessel is in. The fast know. And when it comes to discussion vessels water tight doors to determine if It provides the master and crew with availability of this reliable information of speci? c design elements or processes,
its fourth year and changing Rob Howard email@example.com tion, this too is traditionally where we global trade patterns have conspired to keep rates tight in the big three – the bulker, Web Editor Eric Haun firstname.lastname@example.org seek C-suite insight from the leaders tanker and containership markets. Web
Underwater Drones Join the burgeoning business of Exploration Cruising Norway-based Hurtigruten is a leader in the niche ex- these intriguing waters accessible to guests on board. ploration cruise market, in part for its capacity to enter- Blueye’s Pioneer drones will share video and images of tain
by a pilot. There are also legal challenges There are several hurdles that need to be overcome in or- such as airspace restrictions and increasingly tight regula- der to achieve seamless multi-domain operations where the tions. However, the value that aerial drones have proven to bene? ts of unmanned
or offshore oil and gas. www.fciwatermakers.com to-metal contact. The SmartPlug is available in 30 or 50 amp versions. www.smartplug.com ‘OSCAR’ Vapor-Tight Light Brightens Wet Environments Water- The task of lighting chronically wet Rescue environments like harbor facilities, Training yards and
PRODUCTS NOFIRNO Seals for Diesel Power Pack Exhaust Diesel generators in the form of ready-made power packs in contain- ers are vulnerable to water tightness, particularly around the diesel genera- tor’s exhaust. To prevent this, Beele Damen’s Free Dredge Calculator Engineering supplies exhaust sealing
Coastal Interceptor; 41MMP- piracy, governments have found that agile coastal vessels ? t Maritime Police Patrol; 40RHIB-EC- Rigid-Hull In? at- their tight budgets. able Boat, enclosed; 36RHIB; 35SPC- Swat Patrol Craft; Closer to home, municipalities pooled their precious 35RHIB-EC; 34CCR- Combat Craft
28 • Number 10 arine OCTOBER 2017 www.marinelink.com News M Salvage Spill Response Research & Testing to Meet New Challenges Multi-Mission Workboats Tight Budgets Demand Capable Workboats CADCAM Software Engineering & Design Integrated for Effciency Arctic Operations Response Capabilities to Match
Guam Bolsters Oil Spill Recovery Capacity Lamor recently commissioned its LSC 4C Side Collecting Oil Skimming System for Guam’s Oil Spill Response Operations Company (OSROCO) and T&T Marine Salvage (T&T) making it the largest skimming system in the region. OSROCO, a wholly owned subsidiary of Cabras Marine
of ballast water BWTS offers a modular approach providing h th t t t t e space we can.” discharged during cargo ops every year. further ? exibility in tight spaces. 52 Maritime Reporter & Engineering News • SEPTEMBER 2017 MR #9 (50-57).indd 52 MR #9 (50-57).indd 52 9/6/2017 11:46:36 AM9/6/2017
Capt. Brian A. McAllister Main Particulars & Equipment List Owner ...................................................................................................................McAllister Towing & Transportation Ships Whistle ................................................................................
facilities amongst these systems because nobody’s on an island any- are vast and disparate, and when not integrated intelligently, more. You’re in a very tight competitive market where steam can be unwieldy and vulnerable to failure. Even small failures ship lines are asking for cost control to the ‘nth’
task. Credit risk/credit-worthiness is a big concern for suppliers, who have to carry the burden of cost right through the supply chain. With margins tight, the cost and availability of credit, and the credit-worthiness of customers can both have a signif- cant impact on business. When it comes to managing
MR Products & Services www.MaritimeEquipment.com USCG License Software Affordable - Merchant Marine Exam Training http://hawsepipe.net Freelance Software 39 Peckham Place Bristol, RI 02809 (401) 556-1955 - email@example.com MARINE FENDER & DOCK SYSTEMS RUBBER
said tages when continuously moving equip- less,” said Thompson the Big Apple itself it has a long and Thompson. “In step, there was a big ment through tight maritime spaces. “With the FARO system I can re-model colorful history. The direct link reaches price difference in regards to coatings “Up until
Keeping a Tight Lid on Tier III & Sealing Solutions With more than 90% of global trade carried by sea, shipping is a major bat- tleground in the reduction of emissions. About the Author Tier III is the latest emission standard Omer Raoof is Business Line Leader for pertaining to NOx emissions from
Stoichevski - Scandinavia While the collective market may currently 2,826 vessels on order, representing a cumulative 105,960,703 gt and a value be tight, there are always pockets of of $131.1 billion (for full details, turn to Shipbuilding Statistics on page 46). Looking Production Irina Vasilets
, only have 4 nuts 360 degrees of rotation. This makes installation and main- and bolts to assemble. Of interest to those workboat opera- tenance in tight spaces quick and easy. THE COMPANY: Viega started in Germany in 1899, founded by Franz- Anselm Viegener, who created an innovative new design for
patrol offshore in big water or can dart in and out of tight inland shallows. A favorite of law enforcement and ? rst responders, the stable and forgiving Brunswick Impact RHIB diminishes damage and wear with repeated board- ing of other boats. The durable Sentry aluminum mod- B G C P RUNSWICK OMMERCIAL
BSRM – SeaHoss Chesapeake Marine DA West Marine Products Training Institute 691 Cornwallis Drive 3566 George Washington Memorial Hwy PO Box 968 Mount Laurel, NJ 08054 Hayes, VA 23072 Friday Harbor, WA 98250 Tel: (888) 509-0668 Tel: (360) 378-4182 Tel: (804) 642-0123 E-mail: firstname.lastname@example.org
in drydock is time that any vessel – in any trade – isn’t earning revenues. of the pipe they are attached to. Advantages: Creates rigid, permanent, leak-tight joints in seconds Lighter than standard ? anging No ? ame, arc or cutting oil / or hotwork permit needed Smaller volumetric footprint Simple system
According to the survey, like the many components that warder, my most critical pain point is…” and like last year, the majority of respondents indicated tight margins followed by collectively make up the supply chain, the freight forward- ing market is fragmented; something that is sparking change. rates
, when and how they cars and larger vehicles in the enclosed, ventilated and weather- intend to increase effciencies. The commonality of operating tight Ro/Ro decks. A wide range of container sizes and types can the terminal as well as the vessels that are designed to go into be accommodated, ranging