Lesson Learned Stenungsund

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    BOREALIS LD5 Stenungsund (Sweden)

    Lesson learned

    CONSTRUCTION

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    BEFORE WORKS

    Lesson learned: Stenungsund 2

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    AERIAL VIEW (1/2)

    Lesson learned: Stenungsund 3

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    GENERAL LAYOUT

    Lesson learned: Stenungsund 5

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    Borealis Stenungsund complex area is as a very unusual site for theconstruction of a polyolefines plant:

    a soil composed mainly of solid rock with some deep clay areas

    a very compacted layout at different levels inserted between the rock scarpat east side and the existing plant at west side

    LD5 plant are is very close to running existing plants

    The above, together with other other peculiarities, strongly influenced the

    PROJECT FEATURES

    Lesson learned: Stenungsund 6

    .

    In this presentation however the topics addressed are supposed to be notdirectly related to the above characteristics and have been selected in orderto be implemented in any other LDPE indipendenctly of the geographicallocation.

    In general the presentation is structured area wise where, for each one,

    description / characteristics, erection, sequence and observations /recommendations are described.

    Particular attention shall be addressed to the civil works which are the mostimportant to keep in the right sequence the following disciplines.

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    1) Subdivision of works: it was decided to dividethe civil works in two parts; south package (Silos

    AREA 400 SILOS AREA (1/9)

    Lesson learned: Stenungsund 7

    area) and north package (all the other areas). The

    reason to have two contractors simultaneously atSite was to share the risk between a well knowncontractor (NCC- south part), overloaded at thattime with other ongoing Projects and Pihl (newcontractor without a proved experience in the fieldof technological foundations). It would have beenpreferable to increase the scope of NCC for theentire south part (areas 400, 90 & 100 and pipe

    racks). We faced a non easy coordination issue tomanage the border areas between them

    2) The silos concrete structure was completed withtwo months of delay because of unexpected soilimprovement that was required. to verify if there isa margin to reduce the size of the concretecolumns and horizontal beams.

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    AREA 400 SILOS AREA (2/9)

    Lesson learned: Stenungsund 8

    e ra n wa er ra nage sys em was no

    included in the scope of civil contractor. We shouldadd it in the scope (PVC welded pipes or similar)

    4) The embedded plates have not been fullypainted by the civil contractor (full painting cycle).We shall add it in the scope (sand blasting + 2painting coats)

    5) The temporary elevator to access to the top ofthe silos has to be included in the scope of the civil

    contractor and maintained till the final stair casesare erected (around two months after the civilcompletion of the main structure)

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    6) The silos templates have to be transferred to

    AREA 400 SILOS AREA (3/9)

    Lesson learned: Stenungsund 9

    .template from J&D facing several discrepancies(radius not as per drawing ).

    7) The silos anchoring system should be changedfrom hook type to counter washer type (squareplate 100 x 100 x 15mm). Due to the narrow gapof the main rebars it was very difficult orsometimes impossible to insert the hook typeanchors

    8) Embedded plated shall be replaced (In case ofrevisions or erection mistakes or late drawingssubmission) by external plates fixed by chemicalanchors bolts (to be added in the scope of civilcontractor as option in unit rates)

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    9) Once the main concrete structure is erected thesteel structure priorities are:

    AREA 400 SILOS AREA (4/9)

    Lesson learned: Stenungsund 10

    a) erection of the two stair cases up to top main

    concrete level. The upper part of stair cases shallnot be erected interfering with the silos erection

    b) erection of the handrails at the main concreteelevation

    c) erection of the platforms and stairs under thesilos. The erection shall be done by placingforklifts and mobile platforms (conventionalmobile cranes are not advisable being the space

    very narrow). Due to the huge amount of itemsthe supplier shall present a detailed sequence ofdelivery. We faced several problems in this areacaused by missing handrails, platforms, etc. Theactivity can go in parallel with the silos erection(silos to one side and steel structure to theopposite)

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    AREA 400 SILOS AREA (5/9)

    Lesson learned: Stenungsund 11

    e op connec ng a um num p a orms

    (supplied by J&D) were not included in themechanical contractor scope. It shall be added inthe steel structure erection scope (300t crane isneeded for lifting + 100t with man- basket)

    e) supply and Installation of top silos pipesupports (for Zeppelin systems) were not includedin the mechanical contractor scope. It shall beadded in the steel structure erection scope (300tcrane is needed for lifting + 100t with man-

    basket) f) to verify from engineering point of view that

    buttery limits between the different suppliers(items 9d & 9e) are respected

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    10) Silos assembly observations

    a) Its important to have a suitable assembly areawell compacted of 10,000 m2 minimum. The area

    AREA 400 SILOS AREA (6/9)

    Lesson learned: Stenungsund 12

    since the silos are transportable via low bed

    b) the saddles to transport the silos (differentfrom those needed to store the silos), shall beincluded in the scope of the mechanical contractorwhile those needed to store the silos (woodensaddles), shall be accounted in the silos supplierscope

    c) based on the experience in Stenungsund, withgood weather conditions, the mechanical

    contractor can install one silo a day. It isadvisable to assemble as much silos as possiblemobilizing the main crane (600t crawler crane)when you have a buffer of at least 60% of thesilos (finally inspected) and the remaining silosstill under fabrication (to be completed in onemonth). Obviously this ideal solution wouldinvolve much more assembly area.

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    d) the degassing silos are the most critical onesfor the high finishing requirements. Even

    AREA 400 SILOS AREA (7/9)

    Lesson learned: Stenungsund 13

    exper ence supp er e ace severa

    difficulties to comply with Borealis demand. Wesuggest to start the assembly with the storagesilos first and at 50% of fabrication with thedegassing silos (when you can keep the silos onthe rollers without impacting the rest)

    e) the closing of the silos outlets shall be includedin silos supplier scope (closing by temporarywooded flanges properly sealed)

    f) to keep pressure to silos supplier to get the

    auxiliary structures on time (upper platforms,vertical ladders, etc.)

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    g) it should be asked to the silos supplier toincrease the size of the holes of degassing silos

    AREA 400 SILOS AREA (8/9)

    Lesson learned: Stenungsund 14

    s r o om r ng n or er o prec se y w e

    anchor bolts. For the other silos there is noproblem being them fixed with clamps

    h) we shall verify that skirts erection is included inthe mechanical contractor scope (they are noterected by the silos supplier in the assembly area)

    i) we shall, before the silos erection, when thecivil scaffolding platform is still available, install apermanent internal shuttering (aluminum type)for the final grouting. If not installed as

    suggested, it will take a huge effort at later stage.

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    11) Silos erection

    a) the erection of the silos was performed with

    AREA 400 SILOS AREA (9/9)

    Lesson learned: Stenungsund 15

    600t crawler crane (main crane) + 200t mobile

    crane (man-basket crane). The main craneerected all the silos from the south part shiftingfrom west to east ( we started with degassingsilos). It is suggested to postpone the U/G on thatarea after the heavy lifts

    b) in the mechanical contractor scope we shallinclude the installation of a temporary lift up tothe top of silos. Stair cases even if erected

    destroy the legs if used more times a day

    c) the tilting of the degassing silos involved theinstallation of two trunnions (not foreseen by silossupplier). It shall be included in the silos supplierscope

    d) spreader beam, slings, etc. shall be providedby mechanical contractor, clearly mentioned inthe subcontract requirements.

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    1) Its a simple slab with some foundations

    2) We decided to install first all the equipments

    AREA 090 MATERIAL HANDLING COMPRESSORSTATION

    Lesson learned: Stenungsund 16

    an a er e s ee s ruc ure o ac a e e

    mechanical erection 3) After the equipment installation we erected the

    steel structure up to the purlins

    4) After that (keeping some openings) we erectedthe spools

    5) After that we closed the roof and si

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