GB2335172A - Improving tanker stability and utilisation - Google Patents

Abstract

To resolve the problem of transportable tanks, e.g.road, rail, sea, air undergoing fluid surging, flexible inflatable baffles are filled in the tanks' interiors, tethered at the tanks' neck ring (5) of the manlid; the baffles move freely. Inflation media may be compressed air, nitrogen, carbon dioxide introduced or released by a valve (6) and venting of overpressure by relief(7) valve. Buoyancy lifts the baffles to compress against the tanks' upper parts and against each other, excerting great stability. Low volume loads may be carried in high volume tanks with greater safety and dedicated control of ullage. No tank valves are affected. Inclination of the baffles allows maximum control and adjustment.

Description

1 2335172 TITLE:- A Means of Improving Tanker Stability And Utilisation.

is- This invention relates to method and apparatus for the extended use of existing and new-build rigid. tanks and containers which, by virtue of their widespread use in many countries and situations for a multiplicity of substances, are, by regulations or custom and practice in other countries and situations, rendered inoperable presently. Maximum axle,or gross vehicle weights permitted,vary.

The dangers of liquids surge in tanks used by road, rail, sea, and air. are well understood. Limits of filling to prevent rupture of tanks by excessive developed pressures occurrence, either by ambient temperature rise or by a catalytic chemical reaction.A are well established, as are the pressure and vacuum relief requirements to ensure maximum safety. Free space above the liquids load line, ullage, is, for a wide range of substances considered vitally important, governed by regulations. Compartments of the appropriate size are mandatory in many instances, as are baffles, limiting dynamic surge of liquids below dangerous levels where a tank- could be overturned, shunted forwards'or rearwards.against an intended direction of travel, and in sea or air conditions involving lateral and longitudial movements s imultaneous ly, catas trophy.

Fabrication and installation of baffles and bulkheads to tanks is expensive, as are manlids. Fill and drainage p-kpework and.pressure/ vacuum relief systems to separate compartments becowe an expensive necessity. Cleaning such multi- compartment ed and baffled tankb is far more difficult, time consuming,rnore costly than single compartment unbaffled units which, consequential upon lower manufacturing costs, lower weight, lower cleaning and maintenance costs, offer operators considerable advantages if problems associate4 with liquids surge can be satisfactorily overcome.

Liquids surge has been noted as a matter seriously affecting road tanker drivers' health. Prolonged surge-pulses when braking, at halt, on. hill climbsyinduce serious vomiting, blurring of vision and debility. Cab vertical oscillations jar spines.' In a -tanker-vehicle demonstrable proof. of horizontal force's translation is evidenced., p 2.

It is recognised that many capable drivers refuse work involving road tankers for health reasons in which liquids surge is culprit. e.g. at halt,vertical oscillations 3.8lems x 7+ mins. is a norm to 0.

Attempts to resolve this situation have been made by introducing hollow spheres to float upon the liquids surface inside tanks, thus taking up much of the ullage space. In certain.a few, instances.this approach has merit when problems associated with interferance with valves are eliminated,and ball cleaning and their storage overcome. operators have, for many years, approached tank manufacturers and others in U.K.,U.S.A., Japan and Continental Europeans for possible solutions, without success.

(c) 1 have now discovered a way where the obstacles formerly considered insurmountable may be overcome.

(a) The ullage space in oversize tanks may be adjusted to acceptable limits so as to enable such tanks to comply with regulations and good safe practice with lower loads.

(b) Pressure relief and vacuum valves operations will in no way be adversely affected,neithet will bottom or top loading/ discharge valves or the manlid access/inspection points.

1.1odification to tanks is not considered as structurally significant although load-weig ht amendments, tare weights, and documentation regarding proof tests may be needed. (d) Simplicity of conversion is inherent, as are the features of cleaning, removal, storage, transporting & manhandling.

in its simplest form the invention may be described as inflatable baffles. They may be of any size to meet the operational needs of the mode of transport/storage considered,bounded only by their collapsed uninflated state's capacity to enter tank orifices, either manlids, or specially constructed entry ports if greater -30 than conventional manway sizes. on container tanks conforming to I.S. O. and other norms the invention would be preferably two cylinders made of flexible yet robust materials such as appropz. riate grades of plastics or rubber compounds with additional p 1 0 3 reinforcement at high stress/abrasion points, outer surfaces of which are designed to be compatible with the substance/s to be carried in the tank. Each cylinder is fitted with an. inflation/ deflation port/control valve, pressure sensing and relief controls and appropriate blind caps. In the case of conventional ISO container tanks, such controls would be preferably grouped about each cylindersIcentre line. When positioned in the tank's interior the cylinders would lie one each side of the centre line of the vessel and with all the controls adjacent to the manlid neck ring.

Support st-raps on each cylinder would be of sufficient number and strength to provide adequate attachment of cylinder-to-tank and cylinderto -cylinder if required. so that inflation by personnel in proximity could be effectively controlled. Inflation medium may be by any appropriate gas, e.g. compressed air, nitrogen, carbon dioxide, or other inert gas or mixtures appropriate for the load and commensurate with safe good practice. Positioning the inflation ports, relief valves and gauge housings on an inclined plane to the vertical, ca. 40,0 enables adjustments/ readings via the neck ring when the load's buoyancy lifts the cylinders towards the top surfaces of the tank. Fine adjustments may be necessary or prudent to cylinder pressures determined by ambient or load temperature considerations.

Robust anchoring points may be incorporated in the cylinders construction, determined by the manufacturing processes used, i.e.

with rubber and certain plastics compounds, a bonding process similar to vulcanising may be appropriate. Laminated plastics/fabrics joints may require a special bonding by ultrasonic or heat-ray process techniques. other fabrics may require special thermo-setting or compression jointing medium. If metallic eyelets are preferred as an optimum for certain materials, then such would penetrate only materials designated for that purpose and known to be sufficiently strong for restraint purposes and any additional forces such as may be encountered in removal, lashings for storage, cleaning, or transport. Contacts adhesives would be 'load grade approved'.

e 4.

Mletal snap-links et al may be used to bind cylinder to cylinder or cylinder to tank. Preferably of stainless steel, snap links, karabiners, or D type shackles with non-drop screw pins, would accept all stresses at tether connections at the neck ring zone of the tank, either a spreader 'spider', a detachable item which latches onto the neck ring and, like the neckring's interior iscaptured into. a tank-sealed state when the manlid is lowered and all compressing nuts are secured. Such a 'spider' sprcaddr may be preferred on tanks where welding is an unacceptable means of attachment,e.-. to a stress relieved vessel, or where weld contamination is possible on passivated surfaces,or inverting tanks is impracticable. Welded lashing points may be preferred.

Alternatively the cylinder retaining straps would be attached to the tank by simple bars either straight, or formed into a 100P and welded to the inner face of the manlld neck ring, preferably of circular section and presenting no serious obstacle.. ' Once -loading has-been completed, the elevating straps which held the cylinders in place, may be released on longer tether-r straps or ropes, thus allowing the cylinders to ride where they will within the tank's confines. With the manlid and all valves closed. and sealed the tank may be transported by all normial means, In journeys through tropical regions at differing times of the year, it is quite normal for condensate to form inside tanks, unless precautions to prevent this are made. pressure gauge$ 0 0. P useful in tests and in loading procedures with untrained personnel, may be removed once those responsible are satisfied that the integrity of the installation is -reliable--,in pressure containment. Any. gauge housing may be fitted with a male)r female blank. At the load's destination Customs Seals are broken and the load is discharged. Pressure residual in the cylinders may be released and, after removal of the screwed blank, air -condensate may be drained through the air outlet/inlet,and gauge point, using outer_ end strap/shackle points to elevate for drainage. If disposable r ..;ylinders are preferred then punctures will deflate & release all.

1 1 p It is well understood that pressure losses from tanks with so called 'hermetic seals' occur. Few know or understand the causes and are content to accept the facts. Air bridges fail under a time induced pressure loss when the most sophisticated materials known are used. Balloons deflate. Air filled dunnage-bags have been used in dry cargo containers as a lighter alternative to wooden dunnage, with mixed results; good in small time scales,poor long term.

A feature of the invention is the use of a thin wall, lightweight, inflatable membrane with a close-bonded molecular structure and a high resistance to the molecules of the inflating medium for the various applications; potables, beer, wines, stout, spirits, fizzy-drinks and other similar substances. They comprise one spectrum. In some cases the membrane preferred is,, of - woven material with a substrate of specially selected compound mixes and a superstrate of different compounds, resistant to specialty loads, hygenic. In other applications the membrane may be of a highly dense plastics almost impervious to losses of inflating medium and yet totally compatible with the load for the tar-ks 4DOlymeric elastomeric mix. For the transport of mineral or vegetable oils a reverse orientation may be required in substrates or superstrates to those developed for food grade applications..... It follows that each item in the invention's totality must be reliable in service for the loads intended. From a base number of two cylinders per ISO container tank, the thickness of materials together with the material's folding properties (so as to pass through the manlid neck ring) may require a plurality greater than two.

The word cylinder, either in the singular, or cylinders, plural, has been used to denote the invention; a true shape only when inflated and free from external loads other than its own mass. The application of pressure from the load's introduction to the tank deforms the invention cylinders so they conform to each other and tank walls- to partial ellipsoidal,or frustro-circular, or partial cylinder may be more accurate geometric terms applied.

1 -ii - 0 h Economics,and the development of new materials will, as in the past, determine the optima in materials selection and the labour costs to work such materials. The chemical industry is,reportedly, producing 100 new materials annually. Improved materials- welding 5 processes are inevitable.

The invention anticipates such development and using the 'pillow' shape welded-end configuration in the four, five. or six layout.say,, with filling/discharge on the end areas in proximity to the tank C> neck ring, an appropriate energy absorbtion medium.is created.

In such numbers, and in such close proximity to each other and their means of restraint or location at tank neck rings,_deleting pressure gaugeswould seem advantageous. To that end, the invention may have marks of a permanent kind on the base fabric which, when inflated to its correct pressure,corresponds to a dimension on a tool. The inlet/outlet may be used as regulators, using appropriate procedures for safety and accuracy by venting.

Marking the invention by capacity, displacement, ownership, makers' mark regarding dates, batch nurnbers.and other data required by quality control standards and the like, together with'correct fill markingimay be imprinted in the base fabric where not deleterious to pressure containment4 or the data may be incorporated in a reinforcing pad tos=aps or ties. Alternatively, a separate 'Data Patch' may be bonded to the structure, preferably close to fill points, accessible for inspection by Customs & Excise et al.

Ends to the invention have aninporta-nce, not only in containing the inflation mediun but in acting as a buffer to accept massive forces aenerated by shunting on rail, crashes on roads, and pitch and roll at sea. Whilst torispherical ends would appear an optimum shape, it in no way precludes conical shapes, hemispheres, flatend ends or reverse concavity or convexity. Such shapes, together with the'Pillow' configuration may be necessary as a result of prcgressf of monopoly status being sought by a manufacturer of the invention; ormaterials, machinery, or labour restrictions /limitations.

1 p The invention conceives that entry into tanks by personnel will not be required at any stage of its normal operations of fitting, loading, inflation/deflation, adjustment, or removal. TO that end, all fasteners, straps, and their anchors to the invention whether bonded, welded, adhered or bolted to internally located s tress -dispersal pads or points, may accommodate appropriate length straps or ropes, all of which conform to the appropriate 5-trength, applicable standards of hygene, safety and efficacy.

The loading/Unloading valve/s are preferably one in number to the cylinders, but may be more if structures or tanks so permit or require; (a) to hasten loading or unloading the inflation medium; (b) to accommodate manlids sited off centre, or in the extreme front or rear. The valves are preferably of the springloaded type which is self sealing under normal gas introduction or even finger pressure, yet when that pressure is released a flexible membrane assumes a closed position. A female orifice is preferable, bounded by a robust outer casing, preferably male screw-threaded to accept a mating female protective cap held captive on a lanyard of appropriate materials, e.g. plastics.

A multi-purpose loading/discharge valve capable of accepting all inElation gases is preferable, but where dedicated loads,e.g. beers are required.using C02 from high pressure gas cylinders, then high throughput cryogenics connections may be substituted, or, if preferred, the existing valve.. supplemented as necessary.

To avoid injury to personnel inducting or educing thd inflation media, lances of an appropriate length are preferable4 They are"of lightweight stainless pipe housed within a low temperature insulating outer sleeve. At the loading-valve end of the lance is C) a matching connector/control to the fill port: open-close. At the other end is a quick-acting coupling preferably, with either a male or female head to mate with. a corresponding fit from, any upstream gas source. A shut-off valve may be incorporated in the lance orthe gas supply line; a considered imperative for safety. The lance nozzle is preferably fitted with a valve spring release 0 mechanism to ensure remote closure of, induction/ eduction port.

p 119 Safety relief valves are preferred,made of any appropriate robust materials, preferably plastics copolymers with stainless steel springs and effective rubber seals. The upper or outer part of the valve being capable of dismantling for ultimate hygene cleaning of seals and springs by chemical, radio logic,.,. gaseous. aqutous means. The internal half of the valve is preferably bonded to the cylinder wall and by releasing peripheral screws or bolts from their mating threaded portions, captive in the lower section, breakdown of the valve is simplified, (a) for cleaning and maintenance, (b) for exchanging springs to a higher or lower setting when authorised. The relief valves are, when assembled correctly,compressing into a gas-tight fit the membrane they are to serve. The use of proven existing proprietory valves is anticipated.in the majority of instances. Any gas released from the valve when in service will be the result of severe impact shock/s to the tank in which the invention is located. Unless the tankitself is ruptured, thus releasing any pressure either from the load or from internal vapour pressures, any released gas from the valve would only add to an existing mass. overall pressure internally would not change significantly and, providing the gas inflation medium is commensurate with the substance carried in the tank, the load will in no way be adversely affected. The most widely used inert gases, N2 & C02,are frequently infUsed over chemical loads to create sterility or prevent condensation, at pressures often less than 1 bar 9. Both gases are prominent as direct refrigerants of high volume foodstuffs carried in tanks C> or box refrigerator containers. It would seem logical that, used.n the invention there would be considerable advantages apparent. Working on the premise that there are few plastics materials proven to be resistant totally to gas penetration, if any, the good use of transpiration to balance the gas(as inflation medium of invention) with a further introduction of gas into the tank,via gas lines normally fitted on ISO container tanks., there would come a time when the disparity of pressures would equalise without detriment to equipment or loads. Seals to manlids and valves would yield 1 9 proportional to their ultimate thickness and proximity to any lesser yielding materials such as stainless steel tank walls, manlid neck-rings or valve bodj?.s. It follows, that even on journeys of long duration, or storage over long periods, the invention's gas retaining capabilities could be maintained by an infusion of appropriate gas via the tank's system without recourse to opening manlids. Sampling of product could be made from the tanks' existing external equipment below load line.

It is anticipated that the invention's capabilities may be used, or considered for other applications than forestated; e.g. on road-going and sea-going vessels, and on aircraft use where cylindrical shapes are not the general rule for the tanks shape. Ellipsoid tanks are used for the transport of many petrols. in tankers by road., as are maximum-section tanks. Sea-going craft an,d-,; r;ver barges have generally flatter-walled constructed tanks than the thinner light-weight road or aircraft fabrications.

The general principles of the invention may be effectively employed on a wide range of mobile and statics tanks to good effect if conical or truncated conic or quadri-shapes are adoptedi &--,eh shape and dimensional parirmeters being limited by access or orifice sizes permittingthe location or removal of the invention.

The simplistic state of the invention is-its design, make & use of flexible membrane/s specially shaped and sized to fit into normal ISO container tanks via the manlid in the deflated state, and once located the membranes may be inflated and then to ride upon the liquid load so as to excert a constant pressure on such load. upon the tank walls. and upon each other. all to create a scate of dynamic equilibrium in such tanks only formerly experienced in vessels normally regarded as full of liquid.

The cushioning effect of theenveloped gas upon the load prevents unacceptably large surge effects developing in the longitudinal lateral, transverse and vertical mul ti- directional paths normal liquids in transit would make. Wave forms are diminished in both amplitude and frequency to the order of one sixth of corresponding p to unbaffled compartment loads of equitable proportions.

Such load stability in transit is transmitted through chassis members, springs, couplings, king-pins and body mountings to all parts of the vehicle, including its driver. on hill climbs lack of surge means less gear changing, improved traction, less wear and tear on engines, gearboxes, differentials, and a great deal less vertical and longitudinal movement to the driver of the vehicle, or passengers. Less fuel consumption is expected. The invention has resulted in improved braking, cornering at speeds, from the maximum permitted through to the lower speeds necessary at the negotiation of corners, roundabouts,and an improved halt condition at trafffic-lights or on weighbridges.

Without exception, the drivers and passengers have claimed the invention offers a vastly improved ride and a tremendous aid to road safety formerly not experienced with container tanks.

The invention prov-ides tank operators new.found advantages in countries with lower weight restrictions for a safertransit of small loads in comparatively large tanks presently unuseable.

0 Current British regulations governing the ullage maximum permitted are not clear other than for substances classified as hazardous by ADR/RID: IMO; The Petroleum Spirit Regulations;and specialist areas such as radioactives. 20% maximum ullage is the rule for a majority of hazardous liquidsIMDG code 13.1.22.7: 'Tanks should not be offered for txansport in an ullage condition liable to produce an unacceptable hydraulic force due to surge within the tank,'seems vague, yet it follows that some presumption of regulations application, either by road or rail transport must have been e.j-fected to get loaded tanks to dock areas, thence to the ships. Police, Ambulance personnel and Fire Brigade staff, are all too familiar with the overturned milk truck: water carrier: or similar nonhazardous load blocking roads, occasioning death and injury to the general public. Wine, beers, milk, and aerated waters may not be classified as hazardous substances, but their means of transport certainly can be, and frequently is. It need notbe so.

e 1 1.

p 11 DRAWINGS Fig. 1. Illustrated by general arrangement 2 baf f les in a.20f t ISO container tank. Valves are pressure relief -vacuum(23) relief (mandatory). Crutlet is tank outlet. 1.is the tank shell. 2. is the manlid neck ring. Baffles with dished ends.

Fig.2.. Shows a 4+ baffle arrangement with 'pillowlshape type press welded ends linked together and attached by tether straps/17 to the neck ring.

Fig.3. Shows in greater size and detail the proposed positions of the baffle furniture: - 3. Filling/discharge valve for gases and any condensate. 4. Relief valve, pressure. 5. pressure gauge housing for gauge or blank. 6. Loop for shackles or karabiner fasteners. 7. D shackles or snap link fasteners (karabiners) Fig.4. shows an internal -external 'bolt fixing' to bafflesiG, Snap-links - karabiners 7.

Fig.5. Typicalmanlid and neck-ring 2. Welded anchor bars 9. A Screw activated (bottle screw shown) compression anchor,10.

Fig-6, A proprietory inflation/deflation valve & cap + lanyardy'll.

Fig-7. A proprietory pressure relief valve 12. & 13.

Fig.8. Bulkhead socket.14, Back entry pressure gaugey 15a. Bottom entry pressure gauge,15b.

Fig.g. An integrally, bonded type filling valve with non-return facility and screw release of pressure or condensate.

Fig.10.Various end and side sections of some tank shapeg the invention may be applicable. permutations of compartments not shown. Total separate pages of drawings - 10. Appended Is some physical tests data gathered over 7 weeks limited controlled conditions..A' With baffles fitted. W Minus baffles. july- August 198.

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Claims (1)

1. Detachable baffle/s for ISO or other liquids container tanks to limit load surge comprising hollow cylinders with enclosed ends welded bonded or otherwise joined to present a gas tight whole incorporating loadingunloading valve/s pressure relief valves pressure measurement means together with all means of of attachment release restraint or control within a tank together with a means of inflation/deflation introduction or removal from a tank without need for personnel to enter the tank.

   2. Detachable baffle/s for tanks as claimed in Claim 1 wherein restraint and support means to a tank may be effected where welding is permitted or preferred only to a tank's neck ring.

   3. Detachable baffle/s for tanks as claimed in Claims 1 or 2 wherein welding is not permitted or preferred on tanks.

   4. Detachable baffle/s for tanks as claimed in Claims 1 or 2 or 3 wherein on inflation by the appropriate gas medium additional positional restraint will be applied by tanks' liquid loads by buoyancy pressures against tank walls Detachable baffle/s for tanks as clairhed in Claims 1 or 2 or 3 or 4 wherein personnel are not required to enter the tanks other than for periodic inspections mandatoryy or where swabs for bacterial analysis or similar tests apply.

   6. Detachable baffle/s for tanks as claimed in Claims 1 to 5 whilst robustly fabricated from materials requiring some areas of reinforcement themselves in no way deliver point or concentrated loads to the tank walls in which they are located thereby avoiding tank wall cracking well evidenced'.

   7. Detachable baffles for tanks as claimed in Claims 1 to 6 offering substantial weight improvements in the order of one twentieth the weight of a netallic baffle constructed to Pressure Vessel Codes.

   1 1^ 1 p i C 8. Detachable baf f 1qt f or tanks as claimed in Claims. 1. to 7.

   offering freedom from the well evidenced cracking of metallic baffles in the areas where reinforced apertures in such baffles fail to flex in conformity with the harmony required to meet surge loads in high stress dynamic conditions.

   Detachable baf f leA for tanks as claimed in Claims 1. to 8. thereby offering an end to cracking of cleaning rings on the convex side of a concave baffle of metallic construction where welded to the tank walls and the baf f les concerned and consequentia-1 decontamination of frequently substantial areas.

   10. Detachable baffWs for tanks as claimed in Claims 1.to 9. wherein a vast improvement in road stability and driver welfare/ safety are evidenced during (a) traction on hill climbs: (b) at roundabouts and during cornering: (c) braking either using foot power brakes or parking brake: (d) in emergency conditions.

   11. Detachable bafflus for tanks as claimed in Claims 1.to 10. wherein the liquid load is displaced by medium of a consistency excerting acceptable forces uniformly at given depths thus accepting such uniformity and through the compressible medium of enveloped gases distriblute such forces to tank walls in all directions far more evenly than formerly, Detachable baffles for tanks as claimed in Claims 1.to 11. wherein inert gases e.g. Nitrogen or Carbon dioxide, et al may be used as an h-if lation medium or a combined inflator and bacteriocide as required or a deoxygenator. Conversely the use of C02 is preferred for- carriage of some beers or 'aeratd products. It follows that any transpiration of gas through gas-filled membranes will not deleteriously affect the selected loads. The displacement of liquids loads by the baffles will benefit some wines by exlusion of air. Use of N2 would appear prudent, or. mixtures of air and N2. Detachable baffle/s substantially as described herein with reference to Figures 1- 10.of the accompanying drawings.