ZA200602794B - Apparatus for facilitating new construction and the internal inspection and repair of large vessels, such as recovery boilers and tanks - Google Patents

Description

AP"PARATUS FOR FACILITATING NEW CONSTRUCTION AND THE

INTERNAL INSPECTION AND REPAIR OF LARGE VESSELS,

SUCH AS RECOVERY B-OILERS AND TANKS

Field of the Invention “The present invention rel ates to an apparatus for facil itating new construction and internal inspection and r epair of large vessels, ssuch as recovery boilers and t anks. The apparatus comprises a platform which is verti cally adjustably suspende=d by means of suspensiom cords hanging down from a roof of the vessel, the plat- form being built from at least- two parallel spaced-apart girde-rs, to which the suspension cords are attached, and at le-ast one plank being arraraged perpendicular to the girde=rs and interconnecting tlie same, the plank restimg on thme girders and at least partly covering the same.

Backgground Art

When large vessels, such as recovery boilers and tankss, are to be built and intcernally inspected and peos- sibly" repaired, the large dimensions thereof always make it ne=cessary to use some kind of scaffold or platform, from which the work can be performed in a safe way. Then there= is frequently the problem that the parts included in tlmis scaffold or platform must be inserted through relatzively small manholes in t=he walls or roof of the vessel. Another problem is that the above-mentioned large dimerasions require the use of a large number of scaffold or pl.atform parts so that all parts of the vessel can be reached. A further problem is that the parts inside the vessel must frequently be mounted under difficult cir - cumst=ances, such as high heat inside a boiler. Finally, especially in boilers, there is also the problem that on the one hand scme parts of the vessel can be difficult to reach because of what is referred to as a nose which is to be found in certain boilers, i.e. a projecting portion on one of the side walls of the boiler, and on the other hand that it may be nece ssary to inspect ox repaix super- heaters which are suspended from the roof of the Iooiler % and which between them f orm narrow passages.

UsS-A-5,007,501 disc loses an apparatus, which is especially intended for the boiler in a thermal power station and which elimin ates some of the problems occur= ring in the same. More specifically, a smaller nurmber of parts are required for t he known apparatus than for a traditional scaffold whi ch is erected standing on the bottom of the large vess el. However, the mounting of the prior-art apparatus is s till based on initial moumting from the bottom of the 1 arge vessel, still comprisses a large number of parts th at must be assembled, and does not solve all the problems of accessibility in a =satis- factory manner.

Japanese Published Application JP-A-2000-0546518 discloses an apparatus a s stated by way of introdwiction, which eliminates at leas t one of the problems with the solution according to US -A-5,007,501. The apparatws according to the Japanes e publication thus solves the problem with the initial mounting from the bottom of the vessel, but at the same time its applicability is limit- ed significantly by the fact that the footboard, wwhich is formed of said at least one plank, extends only peerpendi- cular to the girders. Th is greatly limits the appllicabi- lity and safety of the apparatus when, because of an obstacle, a gap must be left between two neighbouring planks.

Object of the Invention

In view hereof, the object of the invention Hs to improve the known appara tus according to JP-A-200%0-054618 in such a manner that th e remaining problems with this apparatus are eliminated and moreover a consideralkly more flexible and safer appar atus is provided, which fer new construction, inspection and repair is universamlly applicable to all types © f large vessels.

Swammary of the Invention

According to the invention, this is achiewred by an agoparatus of the type mentioned by way of introduction, said apparatus being characterised in that the girders a re individually vertical ly adjustable first lattice g irders, to which the susspension cords are attached and which have flat upper sides forming a footboard.

By the apparatus according to the invention compris- i ng individually vertically adjustable lattice girders, w hich have a built-in plank for walking, there is provid- e d, in contrast to JP-A-2000-054618, a safe floor surface a lso along the girders. The lattice girders are insert- a ble in a hanging manner through manholes in the vessel a t any level without necessitating setting fooft upon the b ottom of the vessel. Sai.d at least one plank —is then a rrangeable in any posit® on between two parallesl suspend- ed lattice girders. It will thus be possible te inspect, f rom the thus provided platform, for instance all walls o-f a recovery boiler, i.e. also those above thee above- mentioned nose, or the superheaters of this boiler all t he way up to the roof of the boiler. Owing to the over- 1_ength of the plank resting on the girders (it is longer t_han the normal distance between two juxtapose=d girders suspended at the same lewel), it will be possible within reasonable limits on the one hand to individua 1ly lower and raise the lattice gimders involved and, on the other mand, to follow the contour of the superheater s which in —ourse of time will frequently be very irregul ar owing to t—-he high temperatures occurring in the operati on of the

I>oiler.

The girders of the apparatus are preferab ly rectan- gular in cross-section, and the suspension cor-ds are suitably attached to therm by enclosing holders which enclose the respective g-irders and have an upp er side

MNO 2005/033441 P-CT/SE2004/001420 which has a centrally arranged fastening mezans for each suspension cord. The advantages of girders that are rec- tangular in cross-section are that they ha—ve an excellent load-carrying capacity, that, if desired, -they can easily be connected perpe ndicular to a correspond ing girder of rectangular cross— section, and that outsid_e the vessel they are stackable in an advantageous way.

Said enclosing holders each preferably consist of two essentially C—shaped halves, with the C openings fac- ing one another, ssaid halves having at their upper and lower ends lugs, through which locking cot-ter pins are movable for lockimg said halves together. Thus designed holders protect im an advantageous manner the girder con- struction from being damaged by squeezing especially on the sides and enswure, by extending under -—the girder, that the entire load-carrying capacity of the «girder construc- tion can be utilised.

Preferably, the lugs of the enclosineg holders form at the upper ends said fastening means fo r the suspension cords. It will thus in an advantageous ma nner be possible : to use the same 1 ocking cotter pin both for locking toge- ther the halves of the enclosing holders and for attach- ing a suspension cord.

The halves of the enclosing holders are suitably made of a band material of steel bent to the cross- sectional contours of the girders. Steel Mas the advantage that it is very sstable in shape and has great tensile strength and that. it is easy to weld, which considerably facilitates the attachment of the lugs for the locking cotter pins.

The apparatus according to the invemtion may, if desired, comprise at least one additional girder, which is of the same type as said first latticee girders and is suspended under at least one of those at a fixed dis- tance. It will thus be easy to provide a platform with several storeys.

It will be appreciated that the additiomaal girder suitably should be rectangular in cross-section and that it is advantageous if it is suspended bw enclosing holders, which enclose the girder and which are suspended 5 from the superposed girder by means of suspemsion bands arranged on both sides of the girder.

It will al so be appreciated in view of that stated above that the last-mentioned enclosing hold. ers prefer- ably each consist of two substantially C-shaped halves, with the openings facing one another, said mmalves having at their upper and lower ends lugs, through which locking cotter pins are movable for locking said halves together.

It goes without saying that also the last-mentioned enclosing holders suitably consist of halves which are made of a band material of steel which is bent to the cross-sectional contour of the additional g irder.

The suspension bands that are used for suspending an additional girder from a superposed girder are preferably steel bands, which at their ends have holes , through which locking cotter pins are movable for 1 ocking engage- ment in corresponding holes in the sides off the enclosing holders of the associated girders. The steel bands are also advantageous because of the good tensi le strength of the steel and the fact that the holes formed therein need no extra reinforcement.

It will de appreciated that the apparatus according to the invent ion can be extended further b—y at least one additional gi rder being suspended under twee spaced-apart girders at a fixed distance and by at leas t one tele- scopic plank, arranged perpendicular to th e girders, resting on the additional girders and inte rconnecting the same.

Said at least one plank is preferably telescopic.

The telescopic design makes it easier to adjust the appa- ratus to different conditions prevailing i.n the vessel.

More specifically, the telescopic plank preferably consists of an outer and an inner mutuallswy telescoping

VWO 2005/033441 PCT/SE2004/0=01420

U section, which have downwardly directed U openin gs with ends curved inwards and the projection of which is limit- ed by a pullout-limiting means. The advantage of t-he ends curved inwards is that they contribute to good mutzual displaceability of the U sections since a point charge is avoided. The pullout-limiting means is for natural reasons necessary to prevent the two cooperating WJ sec- tions from unintentionally sliding apart.

Said pullout-limiting means suitably compris es at least one spring-biased pin, which for locking is- arrang- ed to be automatically moved from the inner U section through lock openings in the legs of the U-shaped sec- tions. This solution has the advantage that the pin con- struction is well protected inside the contour o=X the plank, thereby facilitating the handling of the wplank.

Preferably the outer U section has, at an emd which is adapted to rest on a girder, at least one ver tical hole for insertion of a locking cotter pin, whicsh is arranged to engage in a corresponding hole in tlme upper side of the girder. This type of securing of the plank relative to the girder is important especially or the outermost girder of a platform construction.

The suspension cords are suitably chains hanging down from electrically operated telphers arrang-ed on the roof of the vessel. Advantages of chains ar e that, in contrast to wires that are used according tos US-A- 5,007,501, they cannot be untwined and that the=y can be handled with greater accuracy by chain telphers than wires which are wound in layers by a wire winch.

Finally, the telphers are preferably indiwvidually remote controlled from the interior of the vess=sel. It will thus be easily possible to vertically adj-ust indivi- dual girders inside the vessel.

Brief Description of the Drawings

A preferred embodiment of the apparatus amccording to the invention will in the following be descriioed in more detail with reference to the accompanying schemamtic draw-= ings, in which

Fig. 1 is side view with partly broken-away® compo- nents and illustrates paxts of a recovery boilers, in which an apparatus according to the invention is used;

Fig. 2 is a side view and illustrates parts of the long side of a lattice gdrder;

Fig. 3 is a top plar: view and illustrates parts of the upper side of the lattice girder;

Fig. 4 is an end view and illustrates three lattice girders arranged one abowe the other, which are inter- connected by means of steel bands arranged on tlhe sides;

Fig. 5 is an end view and illustrates a first enclosing holder with associated locking cotter pins;

Fig. 6 is an end view and illustrates a second enclosing holder with an associated locking cot®er pin;

Fig. 7 is a top plam view and illustrates parts of the upper side of a tele scopic plank;

Fig. 8 is a side view and illustrates partss of the long side of the telescopic plank; and

Fig. 9 is a sectional view and illustrates ._ parts of the upper side of the pl ank.

Description of a Preferr €d Embodiment

Fig. 1 illustrates jyoarts of a pressure vess=sel 1 for a recovery boiler, in wh ich an apparatus according to the invention is used fo r inspection and repair purposes.

However, it would be pos sible to use the apparatus for the same purpose also in other types of pressure vessels, such as a bark-fired boi ler, or inside a vessel , such as an oil tank. Moreover, it can be used in new comstruction of such vessels.

The pressure vessel 1 in Fig. 1 has, among other things, walls 2 with man holes 3 formed therein, a so-called nose 4 mention ed by way of intrcducti on, a protective roof 5 and a roof 6, from which a number of superheaters 7 are suspe nded.

The superheater 7 constitut-es one of the parts that are of special interest to be exxamined in connecti=on with an inspection. However, they makze such inspection ediffi- cult by ferming, between them, rmarrow vertical pas=sages, which may have a height of sever-al meters and are mpartly positioned above the nose 4. Somme of the passages e=xtend parallel ®o the plane of the dra wing in Fig. 1, and some 8 extend wertically to this plan e. The manholes 3 &re preferably arranged at least at one end of the passages 8.

The apparatus according to —the invention is skaown in Fig. 1 to the right and to thee left in the form of two platforms 10 with slightly different configurations. A common feature of the two platfozxms 10 is that the compo- nents incl uded therein are ident-ical since they cormsti- tute parts of a construction kit which can be exten-ded as desired to be adjusted to the prevailing situati on.

Each platform 10 includes lattice girders 11 a ndtelescopic planks 12 as the main components.

Of the girders 11, the uppermost are horizonta.lly suspended jpoarallel to each other both in the passag-es 8 and outside the same by chains 13 hanging down from elec- tric telphesrs 14 mounted on the r-oof 6 of the vessel 1.

The telphe=xs are remote controlle-d and can advantage=ously be used, for instance, in order t o initially pull ir a girder into the vessel 1 through a suitable manhole 3.

The lower girders 11 are suspende d from the superpossed girders 11 by means of steel band-s 15 which are arranged on both sicles of the girders 11. "The suspension of looth the upper and the lower girders 171 will be described in more detail below with reference #06 Figs 4-6, and time construction of the girders 11 willl be discussed bel _ow with refere nce to Figs 2-4.

The te lescopic planks 12 shown in Fig. 1 rest on girders 11 hanging at essentially the same level, an d extend, seem from above, perpendicular to these gird ers 11. They are thus arranged perpenddicular also to the passages 8 and can therefore be used to reach the poas- sages (those parallel to the plane of the drawing) which are perpendicular to these passages 8. The constru-ction of the planks 12 will be described in detail below with = reference to Figs 7-9.

Fig. 2 is a side view of a part of a lattice girder 11, Fig. 3 is a top plan view of a corresponding p=art, and Fig. 4 is an end view of a plurality of such girders 11. The girder 11, which is rectangular in cross-ssection, 1.0 is made of aluminium and comprises four longitudiral main pipes 16 arranged in the cross-sectional corners. A grid structure of thinner pipes or rods 17, which stab-ilises the main pipes 16, extends between these main pipes 16 in a zigzag. On top of the two upper main pipes 16, &a foot-

M5 board plate 18 is attached, which has a grooved amti-skid upper side 19. At the ends of the girder 11, coup ling means (not shown) of prior-art type can be arrang ed for a possible extension of the girder 11 or for conn ection of a ladder for instance.

For suspension of the girders 11, use is mad.e, as stated above, of chains 13 for the upper girders 11 and steel bands 15 for the lower girders 11. The chains 13 as well as the steel bands 15 are attached, as iss evident from Fig. 4, to the girders 11 by enclosing holders 20, 21, of which the holder 20 is intended especially for the upper girders 11 and is shown in more detail in Fig. 5, and the holder 21 is intended for the lower girders 11 and is shown in more detail in Fig. 6.

The holder 20 comprises two essentially C-skaped halves 22, 23 shaped according to the cross-sectional contour of the lattice girder 11, with the openimgs fac- ing one another, said halves being made of a ben t band material of steel. Said halves 22, 23 have lugs 24, 25 at their upper ends and lugs 26, 27 at their low er ends, which at the upper ends consist of vertically upwardly bent portions of the band material and which at the lower ends consist of tubular sleeves which are weldedl to the band material. A cottex pin 28 is moved throwgh the lugs 24, 25 for attaching the above-mentioned cha ins 13, said cotter pin suitably be longing to a shackle 2 9, into which a hook 30 at the lower end of a chain 14 can be hooked.

At the lower ends, the lugs 26, 27 are prefe rably con- nected to each other by means of a locking cotter pin 31, which is moved thr ough the tubular sleeves and then locked.

The holder 21 als o comprises two essentially

C-shaped halves 32, 33 shaped according to t—he cross- sectional contour of the lattice girder 11, with the openings facing one amother, said halves bei_ng made of a bent band material of steel. Said halves 32, 33 have lugs 34, 35 at their upper ends and lugs 36, 37 at their lower ends, which at Iooth the upper and the lower ends consist of tubular sleeves which are welded to the band material. The lugs 34—37 are preferably conrected to each other by means of locking cotter pins 38 which are moved through the tubular sleeves and then locked —

To attach the above-mentioned steel barads 15 to the sides of the girders 1, the steel bands 15 have holes 39 formed at their ends, and both the holdex 20 and the holder 21 have holes «(0 formed in their sides, through which locking cotter pins 41 can be moved amd then be locked.

Fig. 7 is a top plan view of a part of a telescopic plank 12, Fig. 8 is a side view of a corresponding part, and Fig. 9 is a sectional view of a part of the plank 12 corresponding to the situation in Fig. 7. The plank 12 consists of an outer and an inner mutually telescoping

U section 42, 43, which have downwardly dir ected U open- ings with ends 44, 45 curved inwards, which give the telescopic plank 12 a good load-bearing cap acity. For reasons of safety, the sections 42, 43 have a grooved anti-skid surface 46, 47 and a pullout-limi ting means 48 for limiting the p ossible projection.

1a

The pullout-limiting meams 48 comprises two pins 50 which are biased by means of a leaf spring 49 and which for locking are arranged to be automatically move d from the inner U section 43 through lock openings 51, 52 in the legs of the U-shaped sect ions 42, 43. To allo=w simple release, the pins 50 are fixe=dly connected to a cable 53 whiesh is connected to both pins 50 and thus allowas simul- tanseous release of the two pins 50.

The sections 42, 43, preferably the outer section 42, can also, for reasons of safety, at one end which is ada pted to rest on a girder Z11 have at least one vertical hol e for insertion of a locking cotter pin, which is arranged to engage in a corresponding hole in thee upper sicle of the girder 11.

A person skilled in the art will realise th at the above-described embodiment o f the invention may be varied in many ways within the scope of the claims, and. that the above-described platforms 10, depending on the n-umber of planks 12 that are arranged and the number of gi_rders 11 arranged under and next to each other are usable for most operations which are to be performed in the vessels at is sue and in which a scaffold is required.

Claims (17)

1. An apparatus for facilitating new construction as well as internal inspection and repair of large ves- sels (1), such as recovery boilers and tamks, said appa- ratus comprising a platform (10) which is vertically adjustably suspended by means of suspension cords (13) hanging down fromm a roof (6) of the vessel (1), the plat- form (10) being built from at least two parallel spaced- apart girders (11), to which the suspension cords (13) are attached, and at least one plank (12) being arranged perpendicular to the girders (ll) and interconnecting the same, the plank resting on the girders (171) and at least partly covering the same, characte rised in that the girders (11) are individually ve=xtically adjust- able first lattice girders (ll), to which the suspension cords (13) are attached and which have flat upper sides forming a footboard (18).

2. An apparatus as claimed in claim A, char - acterised in that the girders (ll) are rectangu- lar in cross-section, and that the suspension cords (13) are attached thexeto by enclosing holders (20) which enclose the respective girders (11) and have an upper side which has a centrally arranged fasteriing means (24, 25) for each suspension cord (13).

3. An apparatus as claimed in claim 2, char - acterised in that the enclosing hoelders (20) each consist of two essentially C-shaped halves (22, 23), with the C openings facing one other, said halises having at their upper and lower ends lugs (24-27), through which locking cotter pins (28-31) are movable for locking said halves (22, 23) together.

4. An apparatus as claimed in claim 3, char - acterised in that the lugs (24, 25) at the upper ends form said fastening means.

i3

5. An apparatus as claimed in claim 3 or 4, c haracterised im that said halves (22, 23)

a. re made of a band materia 1 of steel bent to the cross- sectional contour of the g irders (11).

6. An apparatus as cl aimed in any one of claims 1-5, —~haracterised in that at least one additional girder (11), which is of t=he same type as said first Mattice girders (11), is suspended under at least one of hose at a fixed distance «

7. An apparatus as claimed in claim 6, < har - ascterised in that the additional girdesr (11) is rectangular in cross-sect ion, and that it is =suspended by enclosing holders (21) which enclose the g irder and which are suspended from the superposed girde r (11) by means of. suspension bands (15) arranged on bo-th sides of the girder (11).

8. An apparatus as claimed in claim 7, char- acterised in that the enclosing holde rs (21) each consist of two essentially C-shaped halves (32, 33), with the openings facing one &nother, said halves having at their upper and lower encds lugs (34-37), through which locking cotter pins (38) are movable for locking said halves (32, 33) together .

9. An apparatus as <laimed in claim 7 ozx 8, characterised in that said halves (32, 33) are made of a band mater ial of steel bent to the cross- sectional contour of thes additional girder ( 11).

10. An apparatus ass claimed in any one of claims 2-5 and any one of claims 6—8, character ised in that the suspension bands are steel bands (1.5), which at their ends have holes (39), through which locking cotter pins (41) are movable for locking engagement in corresponding holes (403) in the sides of the enclosing holders (20, 21) of the associated girders (11).

11. An apparatus a= claimed in any one of claims 6-10, character ised in that at least one additional girder (11) is suspended under t wo spaced-

apart girders (11) at a fixed distance, and that at least one plank (12) is arra nged perpendicular to the girders (11) and interconnecti ng the girders (11), said plank resting on the additional girders (11) and at least partly covering the same.

12. An apparatus as claimed in any one of claims i-11, characte rised in that sadd at least one plank (12) is tele=scopic.

13. An apparatus as claimed in claim 12, char- 1 acterised in that the telescopic plank (12) con- sists of an outer and an inner mutually te lescoping U section (42, 43), which have downwardly di rected U open- ings with ends (44, 45) curved inwards and the projection of which is limited bw a pullout-limiting means (48).

14. An apparatus as claimed in claim 13, char - acterised in that the pullout-limi-ting means (48) comprises at least one spring-biased pin ( 50), which for locking is arranged te be automatically mcaved from the inner U section (43) -—through lock openings (51, 52) in 2€@ the legs of the U-shayed sections (42, 43) .

15. An apparatus as claimed in claim 13 or 14, characterised in that the outer= U section (42) at an end which is ad apted to rest on a girder (ll) has at least one vertical hole for insertion of a locking 2 5 cotter pin, which is arranged to engage ir a correspond- ing hole in the upper side of the girder «l11).

16. An apparatus as claimed in any ore of claims 1-15, characte rised in that the suspension cords are chains (13) hanging down from electrically ope- 3 0 rated telphers (14) wwhich are arranged on the roof (6) of the vessel (1).

17. An apparatuss as claimed in claim 16, char - acterised in that the telphers (14) are indivi- dually remote control led from the interiox of the vessel =®5 (1).