Shell & Tube Heat exchanger
The points that are required to be checked while reviewing Shell & Tube Heat exchanger. The list is not exhaustive but provides a simple guideline for the beginners.
- Check Pressure Design Code to be applied and Applicable local regulations to be applied.
- Check completeness and correctness of information, dimension, impingement plate, gasket recommendation, applicability of IBR, TEMA type and configuration, etc. are available on data sheet.
- Maximum design temperature and minimum design metal temperature
- Ensure latest issue of process data sheet is followed.
- Check if any specific note to be highlighted like anodic protection or sloping shell, any special service requirements like NACE/Sour service etc. are applicable which puts restrictions on material requirements.
- Ensure adequacy of shell Internal Diameter to accommodate all tubes with given pitch and orientation, required number of tie rods, considering provision of impingement plate, minimum U tube radius and groove width, ligament as per TEMA recommendation is checked before starting design work.
- Design codes including wind, seismic load and any reference books with edition number and year of publication and amendments if any have been specified and used in the calculations.
- Applicable standard specifications, Job specifications and standards with their revision numbers.
- Nozzle schedule indicating size, rating and nozzle neck thickness, projections and surface finish of gasketing surface of nozzle flange (projection to suit insulation thickness and facing to suit gasket material), Nozzle location, Orientation etc.
- Test pressure including any temperature correction
- Drawing block, drawing number and distribution is in line with project procedure.
- Reference drawing numbers of standard drawings are indicated if details are not given on the drawing.
- Reference data sheet number with latest revision is indicated on drawing.
- Provision of Instrument connection as per TEMA and Provision of vent drain connection for testing
- Support details (lugs, saddles) indicating size, numbers & PCD of foundation bolts. Foundation bolts to be specified with their size and thread pitch in mm.
- Typical applicable weld details of plates, Nozzles and other attachments depending upon material of construction., thickness of parts. (Special attention required. for cladding / lining)
- Provision of standard attachments like Name plate, Earthing boss,
- Tube expansion requirements for strength welded tubes.
General notes – Adequacy and applicability of general notes to be checked
- Ensure that the statement “In general the provisions of ASME / TEMA have to be followed in addition to the local company specification.”
- On-site storage required for more than 12 months prior to installation.
- Surface preparation and painting, surface finish of flange faces with respect to specified gaskets to be specifically checked
- In case of stacked heat exchanger, note stating that final hydro-test shall be conducted in stacked condition must be added.
- Surface preparation and protection requirements
- For stacked heat exchangers, requirement of shim plates as required for adjustment shall be included.
- Sliding support anchor bolts should be hand tightened and for high temperature exchanger Teflon / graphite/Stainless steel sheet below sliding saddle to be indicated with responsibility of its provision by supplier.
- Grooving requirements for shell side clad tube sheets.
- In case of cryogenic exchanger, wooden saddles/Foam glass of adequate thickness below saddle plates to be indicated.
Check TEMA minimum requirements with respect to –
- Shell, channel thickness,
- Tie rods – Nos. & diameters.
- Baffles – thickness
- Partition Plates thickness
- Grooves /Steps
- Tube Holes, Bolt size,
- Impingement Plate,
- Minimum gasket width & minimum acceptable bolt diameter.
- Check if test ring is included for ‘U’ tubes kettle type & floating heat exchangers. Testing arrangement as required for other types have also been included in supplier’s scope.
- Chemical cleaning connections requirements, Thermowell connection requirements, Pressure gauge connection requirements
- Check if lifting lugs, jack screws, locating pins are provided.
In case of ‘U’ tubes
- Smallest radius of tube bend not to be less than 1.5 times O.D. of tube
- Check requirement of Heat Treatment for inner two rows for C.S. tubes bend
- Check requirement of solution annealing of S.S. tube bends
- For large diameter bundles check for U-tube rear support requirements.
- Check tube to tube-sheet joint critically with respect to joint requirements as per ASME sec. VIII div-1 appendix ‘A’ provisions.
- Check details for Tie rods, spacers, runner bars, sliding strips, sealing strips (if applicable are indicated)
- Check vent/drain notches are provided on baffles in Horizontal Heat exchanger.
- Check if pulling/lifting arrangement is provided for removable tube bundles and clear space required for pulling bundle is shown in dotted in schematic.
- Check vent/drain holes are provided at highest & lowest points on pass partition plates.
- If expansion bellow is required, proper details are included for design by specialist vendor including the applicable design codes.
- Vertical heat exchangers which requires expansion bellows, a note near expansion bellow sketch must indicate the minimum civil cut-out size required to clear the tie-rod lugs (For this purpose assume that the bellows design by vendor will have the tie-rod provision)
- Check section lines are appropriate for materials of construction.
Hold List
- Instrument Nozzles
- Orientation of nozzles
- Orientation of attachment like a) Lifting lugs b) Name plate, Earthing boss
- Orientation foundation bolts / support lugs / saddle & Position of fixed & sliding support
- Check completion and correctness of Nozzle Orientation
- Specific requirements of relative locations are maintained as per process data sheet
- If some special gasket or its equivalent has been specified, fix the criteria of equivalence in job specification.
- Post weld heat treatment required for process reasons or for weld overlaid bonnet or channel
- Ensure that nozzle orientation also indicates the expansion bellows tie-rod lugs orientation
- Ensure that squad-check comments are incorporated
- Ensure that drawing is in line with P & ID and equipment modelling.
- Number of cycles to be considered for bellows expansion joint design.
- Fatigue analysis required for flanged and flued expansion joint, and number of cycles to be considered.
- Additional requirements for low chrome steels in high temp. or high-pressure hydrogen service.
- Materials of construction.
- Weight (empty, full of water and operating)
- Painting requirement.