Disini saya coba untuk membandingkan mengenai pengecekan terhadap isometric drawings. Dan tentunya setiap perusahaan akan berbeda tata caranya tapi intinya tetap sama yaitu agar isometric drawing yang dihasilkan menghasilkan hasil yang baik dengan quality drawings yang baik sehingga dapat dipahami pada saat constrcution atau fabrikasi..
Disini saya akan coba menjabarkan dahulu atau mengambil sample beberapa isometric yang berlaku di beberapa company dan juga yang ada pada internet yang saya search baik di goggle atau di yahoo.
Dan ada bebrapa check list yang pernah saya share dan saya masukkan kembali di dalam "Piping Isometrci Check List Selayang Panjang" ini
Berikut adalah beberapa check list pada tiap-tiap pandangan yang berlaku pada engineering company ataupun client.
A. CHECK LIST YANG BERLAKU DI PERUSAHAAN A
Kalau dilihat dari urain yang ditulis dibawah ini, apa yang tercantum tersebut adalah beberapa yang pernah ditemui pada saat mengecek isometric drawing tapi bisa juga dipakai sebagai acuan atau check list.
01 - Color code not used properly
02 - Data block not completely filed in
03 - Data block not checked
04 - Line continuation not checked
05 - Unrecognizable symbology
06 - Audit checklist not filled out completely or not filled out correctly
07 - Piping components that are incorrectly listed in the parts list categorizing them as shop, field, field assembly
08 - Field welds shown at every weld on a field fab iso
09 - Field welds omitted - especially at sheet continuations
10 - Checker made notes to self or others that were in red instead of black or blue
11 - Checker did not make himself clear in what was required, he used an ambiguous narrative statement rather than detailing and locating
12 - Steam trap piping checked without any standard or job instruction
13 - Impossible dimensions either PDS-generated or annotated - for example a gate valve 6mm long
14 - Incompatability of piping components - for example a copper tee on a carbon steel header
15 - Pipe guides and their locations not checked
16 - Checker takes the time to write a note say ing a flow arrow is needed rather than just drawing it in red
17 - Vents and drains drawn in red but not located
18 - Dimensions changed for one millimeter
19 - High point vent specified as a sockolet and a screwed plug
20 - Unneeded field welds added by the checker
21 - Hydrostatic vents and drains missing
22 - Flanged valves added by the checker without locating dimensions
23 - Isometric checked with instrumentation on hold
24 - Duplication of dimensions by the checker - added to existing dimensions
25 - Piping components called out as required by the checker but not drawn or located
26 - Notes by the checker in red - "install drain", "clarify valve size and rating"
27 - Items added in parts list but not shown on the iso
28 - Checker added dimensions in red but also the word "approximate"
29 - Checker spent time correcting the quantities in the parts list
30 - Checker circled something in red with either the note "fix" or with a question mark
31 - Text is too small
32 - Screwed plug welded to valve
33 - Iso checked without stress sketch
34 - Mark numbers missing
35 - Checker marked up the parts list and nothing else
36 - Notes on the iso in black pencil that should be shown in red so the backdrafter will pick them up
37 - Checker is unsure if line is sloped (a note with a question mark)
38 - Parts list receiving more attention than the data block or graphic portion
39 - Steam/condensate break in the wrong place on a steam trap iso
40 - DUMB NOTE; "Reverse the flow" is written rather than drawing a red flow arrow
41 - An iso to be deleted is indicated as such with a post-it that can fall off instead of marking directly on the iso
42 - Lots of checker activity/marks in red on backcheck print
43 - Duplicating a red mark with a note saying EXACTLY the same thing
44 - Socketweld valve is field and needs FW on both ends of the valve
45 - Red question marks in the data block
46 - HOLD shown in black pencil
47 - 100mm long spoolpiece added between every place where fitting make up could be used
48 - A bend is shown but without a callout or radius
49 - Common BOP not called out at dummy supports
50 - Control valve manifold block valve and bypass not in proper location per jo standards.
51 - Lack of common sense...3 BA's in a configuration 2 meters long - two are sliding and one is fixed
52 - Steam trap piping that is not initially shown on the check print should be handled either by the checker drawing it in red or returning it to the designer to have it added for check - NOT just circle it up for the backdrafter to do
53 - Screwed gate valve has a plug welded to it
54 - Line needs future connection - checker says it's to be added but doesn't locate or detail it
55 - Line was checked without IDP being run
56 - Shoe has been deleted but the dimension remains in place
57 - FFW used on 1 1/2" pipe
58 - Expansion loop shown on a line not requiring stress analysis – IA header
59 - Field fab piping with mark numbers
60 - Steam trap at control valve manifold shown after the downstream block valve
61 - Modified support detail dimensions are mixed - some are in millimeters some are in inches
62 - Spec break shown at the weld of a weld neck flange
63 - Weep hole for relief valve to atm is in the side of the elbow
64 - The checker detailed rebar in a CPS
65 - Schedule of pipe being supported is called out on a support detail
66 - Check print already has been signed off - prior to check
67 - Header block valve is too far from the header
68 - Blow off valve missing at y-strainer
69 - Pipe is unsupported
70 - Horizontal line resting on a 5FS1S1 is u-bolted when it does not need a u-bolt
71 - Checking time for iso on audit status sheet says 5 minutes for a complex line
72 - Bolts and gaskets were removed from one sheet and were not added on the
73 - Pipe at minus 50 degrees but not requiring stress analysis
74 - Checker invented own library of symbols for audit status sheet - without explanation
75 - Bolt hole note stating industry standard is unnecessary
76 - Support detail shows insulation on the line, but the line is uninsulated
77 - 55 meters of straight pipe with out attachments of any kind are shop fabricated
78 - New dimension added in red, but old dimension is not deleted
79 - 5G1 used on a line w/3" thick insulation - can't be done
80 - MISMATCH - audit checklist if for a different line number than the iso to which it is attached, yet the marks on the checklist match those on the iso
81 - Work point elevations at elbows and slope plus distance traveled do not "work" - can't be built
82 - Incomplete U-bolt call outs
83 - Weld dot shown on threaded connection
84 - Shop fab supports shown in field fab portion of parts list
85 - Galvanized, threaded pipe with galvanized malleable iron fittings shown as shop fabricated
86 - Undimensioned mark number
87 - Dimension locating shoe places one end of the shoe past the centerline of a nearby 90 degree ell
88 - 5US used in a horizontal run. 5US used on galvanized pipe.
89 - Span charts not adhered to for proper support.
90 - Signing off iso's that have ERROR READING DATABASE on the parts list
91 - Elbow that is rotated but does not have the offset dimensionally called out.
92 - Insulation breaks that are unnecessary between header and vent.
93 - Incorrect item codes for pipe that is purchased pre-painted.
94 - Incorrect fab code for base supports and shoes.
95 - Carbon steel shoe on a stainless steel line. Putting shoes in the field that should go in the shop.
96 - Incorrect or no line continuation called out.
97 - Incorrect choice on PWHT / seal weld / fabrication category in the title box.
98 - Dimensions that can not be read.
99 - Not placing low point drains and high point vents on the shop portion of rack ISO's.
100- Noting PP for insulation for lines that do not require it.
101- Not maximizing spool piece sizes for shipping.
102- Placing field welds below platforms making welding more difficult than necessary.
103- Spool pieces that exceed shipping box size.
104- Checker spent time correcting "cut length" on bill of material.
105- Process drains left off.
106- PLSR not verified for completion.
107- Continuation at equipment not verified with latest nozzle report.
108- Not following standard for insulation lugs.
109- Incorrect call out for insulation lugs.
110- Not using coupling to join small bore pipe together.
111- Addition of couplings for pipe that is "T & C"
112- Not following assembly details for instruments.
113- Incorrect nipple length to get assembly outside of insulation.
114- Not sequencing P & I D with regard to branch location.
115- Handwheels not accessible.
116- Placing a FW in the middle of a pipe run (because of change of partition) rather than at a flange or fitting.
117- Breaking spec at the weld of a fitting rather than the valve.
118- Guides that are too close to a change of direction
119- Flow arrows on dummy supports and support stanchions.
120- Not meeting the minimum required size for dummy support.
121- Not utilizing bends in suitable locations where spec calls for them as PREFERRED FABRICATION"
122- Using short spool pieces that place welds too close together.
123- Incorrect boot size on the steam header.
124- Using 300# weld neck flanges instead of orifice flanges where required.
125- Adding a spool piece where high point vent could have been placed on the elbow (minimum from the weld).
126- Ignoring constructability issue when penetrating a platform.
127- Not giving enough clearance between insulation and grade.
128- Placing loose items like nipples in the shop
129- Making a FW at the large end of a reducer.
130- Creating pockets by using concentric reducers.
131- Not providing weep holes in tail pipes that vent to atmosphere.
132- Not showing dummy support on parts list.
Itulah tadi uraian mengecekan isometric yang berlaku di perusahaan A. Dan berikut kita masuk pengecekan isometric drawing yang saya search dari internet.
2. ISOMETRIC DRAWING CHECK LIST VERSI UMUM I
Berikut ini adalah pengecekan isometric drawing yang berlaku umum. saya bilang berlaku umum karena saya lihat di blog piping yang menuliskan bebrapa hal mengenai pengecekan isometric drawing. Rinciannya adalah :
· Title block.
· North arrow orientation.
· Line continuation - Iso index.
· Matching isometrics and elevation.
· Equipment location to grid.
· Equipment terminal details.
· Location to grid/equipment.
· Structural penetrations.
· Locations of item .
· Line content.
· Flow arrow.
· Pipeline number and elevations.
· Fabrication type.
· Dimensional completion.
· Valve orientation.
· Fabrication limits.
· Field weld locations.
· Make-up weld locations.
· Cut to fit dimensions.
· Spool number sequence.
· Pipe support locations.
· Hydrotest requirements.
· Flushing requirements.
· Insulation limits.
· Heat tracing limits.
· Piping bills of materials completeness.
· Piping insulation materials completeness.
· Specials list completeness.
· Assemblies list completeness.
· Tagged item list completeness.
· Fabrication requirements completeness.
Itulah tadi pengecekan isometrci drawing berdasarkan salah satu blog yang bernah saya baca. Dan ketiga adalah pengecekan isometric drawing yang berlaku di perusahaan B.
3. ISOMETRIC CHECK LIST YANG BERLAKU DI PERUSAHAAN B
Di dalam perusahaan B ini ada sedikit perbedaan dalam hal pengecekan isometric drawings tapi walaupun berbeda tapi tetap tujuannya agar drawings bisa dibaca dan menghasilkan sesuatu yang bisa dibaca dan dikerjakan pada sat konstruksi atau fabrikasi.
Berikut adalah check list yang berlaku tersebut :
- Conformity with PID regarding:
· Piping class & Diameter
· Connections to other lines (qty, size & location)
· Connections to Valves and equipments (weld or flange)
· Instrumentation (type, quantity, location
· Flow direction, slope
· Checking of Material Specification w.r.t Pipe Class Manual
· Location with regard to the building Rows-Columns reference axes
· Orientation of bosses with required details (sectional view)
· Support Lugs welded on pipe with required position and orientation details, if applicable
· Spooling, assessment of Field / Shop welds, with regards to the transport gauge (11,5m* 2,5m*2.5m)
· Clear quotation of orientation for the vertical parts as requested for the slope (e.g. Drain leg to be vertical whatever the main piping slope)
- Conformity with material list MTO available in EPC’ystem (Qty/Size)
· Pipe Lengths
· Elbows (LR or SR, 90° or 45°)
· Tee’s (equal or reduced or tee + reducer)
· Reducer’s (concentric or eccentric)
· Branch connections (Piping class rules = GS140, tee or weldolet or pipe to pipe or reinforcement plate)
· Drain leg (pipe + cap BE + weldolet for LI or drain + half coupling + SW cap + boss for temperature)
· Flanges (type, face profile, size & rating, gasket, bolts)
· Special accessories (quick coupling, flow nozzle …)
· Boss identification / Instrumentation Stubs, GS040
· Valve type, connection and dimension
Dan setelah anda baca tentunya cukup aneh bukan? karena rada agak berbeda dengan seperti yang saya sampaikan di atas tadi. Tapi tujuannya tetap sama yaitu untuk menghasilkan gambar yang baik dan bisa pakai untuk fabrikasi.
4. PIPING ISOMETRIC CHECK LIST
Disini akan diuraikan mengenai check list piping isometric drawing.
- Pastikan Line sizing, Line Class dan changes with P&ID
-Tanda Panah untuk arah flow yang berjalan
-Instrument and Item TAG No.
-Correct Tag No for special items
-Pastikan slop requirement of Pipe
-Check instrument tapping point and branch line follow order according to P&ID
- Show general note and special notes on P&ID
-Pastikan tittle block and revision no. as per manual
-Patikan line no or drawings number ada
-ensure perform of stress check
-Confirm the paint code, insulation code, and thickness and the bondary of insulation as per project spec.
ensure steam tracing code with P&ID
-ensure the design pressure and temperature with line table
-ensure the operating pressure and temperature with line table
-ensure test pressure and test medium with line table
-ensure area no. and Unit no.
-ensure reference plan drawings no.
-ensure NDE class
-ensure state north arrow direction
-ensure issue/revisio no.
-ensure the description for continuation
-dimensions, elevation and coordinates
-spetacle blind orientation
-orifice tap orientation and scope of supply
-orientation of valve handwheel for easy operation
-dimension around control valve
-type vent and drain and the location for easy access
-the correct type and description of weld attachement support.
-flange rating size and code equipment nozzle
-the reflection of final vendor drawing package
-reflection of final vendor drawing dor in line instruments
-location of flange bolt hole on equipment nozzle
check the interface between control valve actuator and by pass line.
-confirm flange rating size and code fot control valve and instrument valves
-piping thickness as per specification
specification of piping material
-tag valve no.
-pastikan thickness of gasket
valve type of instrument connection (integral valve and double block and bleed)
-possibility of temporary strainer
-requirement of branch reinforcement
-consider for field weld point jika diperlukan
-ability of handling oand transportasi of spool pieces
-ensure teh enough space for bolt tightening for valve and flange over 24" and 600 psi.
-the maintenance of screen of large bore cone strainer
-ensure the design of break flange for lifting of pipe spool from Top Nozzle of Exchanger
-confirm the butterfly valve type on tank nozzle
-requirement jack srew hole of specer blank
-The maintenance for direnction of T strainer
-Location of drain point of stainer for full drain
-ensure the specification of material with line class
-confirm bill of materials with line class
-confirm bill of material with drawing
-state the BOM of special item
-Bill of materials for Bolt and Nuts gasket on equipment nozzle
-scope of supply for bolt and nuts for instrument items
-Type small valve with flangeed w/nipple for heat treatment systems
-Bolt length with flange thickness materials
-special bend for jacket line above 12"
-design half cutting pipe and fitting for jacket.
Itulah tadi 4 buah pandangan mengenai isometric drawings check list dan kita bisa lihat sendiri mana yang sama dan mana yang berbeda. Tapi yang perlu diingat adalah aturan perusahaan lah dimana kita bekerja yang harus kita ikuti walaupun apa yang dibuat sangat berbeda saat dimana kita bekerja sebelumnya.
Dan apa yang saya uraikan diatas mengenai isometric check list, ada lah yang saat ini berlaku di masing-masing company.
Dan bila ada kesamaan berarti itu adalah check list berdasarkan standard piping yang berlaku dan bila ada perbedaan anggap saja sebagai kemauan perusahaan untuk menerapkan hal-hal yang lebih baik dalam pengecekan drawing.
KL, 8 Agustus 2011, at 11.15 PM