DESIGN OF NOZZLES

Uptill 2 nozzlesuse type 1 3 nozzles or aboveuse type 2 or others except type 1 Always use blind with manhole 2 nozzles can be used with pad in cases where the design is failed without pad. Minimum width of pad must be 50 mm. Do not use LWN flange until and unless it is said by client (e.g in case of 2 nozzles sometimes the nozzle design is failed by choosing type 1, then choose type 2 and minimum width of wear plate or pad should be 50 mm but do not use LWN flange with 2 nozzle). LWN flange is used with 2 nozzle or nozzles having more than 2 dia only when client demands While calculating the nozzle schedule use pipe schedule table If nozzles are having 16 dia or less, then use pipe schedule table and choose feasible pipe schedule according to nozzle dia requirements. For 16 dia nozzles or lesser, choose Seamless pipe. For more than 16 dia nozzles always make them with the same thickness plate which is being used for vessel and such kind of nozzles would be of welded pipe. For more than 16 dia nozzles, choose Nozzle OD from Pipe schedule table corresponding to the nozzle dia. For more than 16 dia nozzles, While entering nozzle detail in compress, if we choose ID then subtract twice the thickness (chosen thickness) from nozzle OD (taken from Pipe schedule table) and then put this value in compress.

Always remember that for 24 Man ways, choose the nozzle thickness as 12.7 (which is extra strong pipe schedule). If it is required by client that use OD of nozzle as ID then take ID of nozzle equal to OD and choose some nominal pipe thickness from pipe schedule table.

DESIGN OF INSERT PLATES

Insert plates are used to increase area re-inforcement for nozzles to get proper design. There is no any advantage to increase pad width (for getting more area re-inforcement in case of nozzle) more than the limit (mentioned by compress by red dotted rectangle). If such a case occurs when nozzle design is being failed prior to approaching the maximum pad width limit then use insert plate. The concept of insert plate is that a new plate of thickness more than shell thickness is added at the area where a nozzle is present.

Calculation of Insert Plate Dia:

Method # 1

Limits of re-inforcement per UG-40 (message on compress calculation page for particular nozzle design)

D = 615.6 mm (say) = 650 mm (approx)

& Dia of Insert Plate = 2 x d = 2 x 650 = 1300 mm

Method # 2

Limits of Re-inforcement along the vessel wallLR=440 mm (say)Dia of Insert Plate = (2 LR) + (Nozzle dia) = (2 x 440) + (1250) = 2130 mm = 2150 mm(say)

NOZZLE LOADS

Different forces (stresses) and moments acting on nozzles due to external loading (Fluid flow) are given below

Pr=Radial forceMc=Circumferential momentVc=Tangential forceML=Longitudinal forceMt=Torsional momentFr=Resultant Shear forceMr=Resultant Moment

In order to add loads on nozzle while designing in compress, we proceed in different manner for heads and shells.

AT TOP/ BOTTOM HEADS:

Pr = -FaM1 = 0V2 = 0Mt = MtV1 = Fc + FLM2 = Mc + ML

AT SHELL:

Values are taken directly from table according to given nozzle dia and rating as.

FL = VLMc = McFa = VaMt = MtFc = VcML = ML

Note:If client has given nozzle loads in the form of any table or chart then always use Those values. If not given then demand from client. If still not available then use The standard table and take values as an approximation for calculating nozzle loads.

SELF-REINFORCED NOZZLES & FLANGES

In pressure summary during calculations of vessel on compress, MAWP should not be minimum for nozzle reinforcement. Minimum value of MAWP is only acceptable for shell or heads If MAWP of a particular nozzle is more than shell or head but in nozzle detail, there is warning that available re-inforcement governs the MAWP of nozzle; then ignore this message as the nozzle is already safe. However if MAWP of a particular nozzle is minimum and in nozzle detail, there is a warning that available re-inforcement governs the MAWP of nozzle then either increase re-inforcement of the nozzle by any of the following steps.

Increase barrel thicknessPut insert plateIncrease the shell thickness (if coarse length is not to long

If MAWP of a particular nozzle is more than shell or head but in nozzle detail, there is warning that local stresses at the nozzle OD governs the MAWP of nozzle; then ignore this message as the nozzle is already safe. However if MAWP of a particular nozzle is minimum and in nozzle detail, there is a warning that local stresses at the nozzle OD governs the MAWP of nozzle; then change Nominal Thickness of the nozzle.

If more than two self re-inforced nozzles are present on shell and their design is failed despite of increasing barrel thickness up till maximum level then rather than to use insert plate, use a proper length of shell coarse like 2000 mm or max of 2500 mm and increase its thickness up till the value where nozzle safe design is achieved. In case of single self re-inforced nozzle which is being failed despite of putting heavy barrel thickness, insert plate can be used and is more feasible. For ARAMCO always use series A flanges unless stated otherwise. If during flange calculation, the size of flange is falling within the standard limitations then always click on standard flange (B 14.7) in Appendix 2.0 flange option. If a BOOT is attached with the vessel and it is required by the client that attach a flange with the boot, then it is made in two portions.

(a)The upper side of flange and portion of the boot attached with vessel are designed with the vessel. The portion of the boot is considered as a nozzle and designed while going in nozzle option

(b) Whereas the lower portion of the boot, the lower side of flange and boot head (and any nozzle attached with this portion) are designed in separate file with the same design conditions as of vessel.

The boot is considered as shell and attach Appendix 2.0 flange with standard specifications (if dia is not larger e.g. 40 and available in the list of standard B14.7 flange option in Appendix 2.0 flange.

Add liquid level in this separate portion of the BOOT having value equal to I.D of vessel + Total length of boot.

If boot head is provided with nozzle then add nozzles loads to the upper part of boot by adding the nozzle effect. WRC-297 can be done on compress as well.

Action -----perform FEA calculations-------Options If in PV-ELITE during analysis on WRC-297, the following warnings come then ignore themThe ratio Dn / Tn 20Check the limitation of WRC bulletin 297

Dn / Dv 0.5Check the limitation of WRC bulletin 297

Dn / Tv 5Check the limitation of WRC bulletin 297

WRC-297 can be done for self re-inforced nozzles in the similar manner as done for normal nozzles. Just insert the thickness of nozzle nominal thickness (tn) rather than to insert heavy barrel thickness. LWN is also a type of self re-inforced nozzle so if client demand self re-inforced nozzles with lips then we make the sketch of LWN with lip as well.

SKETCHING SELF RE-INFORCED CONTOUR NOZZLES

In order to make sketches of self-reinforced nozzles we proceed as follows.The standard sketch of lip nozzle is attached. There are different dimensions being Mentioned on it like A, B, C, D, H, H1, L & R.

A, B, C, & H can be directly obtained from the calculations of particular nozzle from compress. R is the shell radius (single curvature) in case if the nozzle is attached with the shell and 0.9 D or 0.17 D if the nozzle is attached with the head. D, H1 & L can be calculated as follows.

Calculation of D

Length of lip = R + 10 + (tan 30 x shell Th.)

Take minimum value of R as 19 mm. however R is variable depending upon the weld Size as can be seen from ASME Sec VIII DIV 1.0. It should be selected such that it is tangent to the fillet weld.

EXAMPLE:

Take R = 25 mm (approx.)&Tan 30 x Shell Th. = Shell Th. (approx.)

If Shell thickness is 20 mm & C = 856.6 mm, then

Length of lip = 25 + 10 + 20 = 55 mm

So D = C + (2 x length of lip) = 856.6 + (2 x 55) = 958.6 mm Calculation of H1

H1 = H + X + Z

Where H = Height of barrel (Normally taken as not more than 50mm during calculations in compress)

Z = Length of nozzle starting from the end of taper of barrel to final Spray point of nozzle

(Normally from cost reduction point of view, Z is taken to be 50 mm in this way the forging dye will be less expensive and the rest of the length of the nozzle is fabricated separately and is welded to the forged nozzle whether seamless or welded from plate)

X = Y x Tan 45Y = Barrel Thickness Nominal Thickness of nozzle

EXAMPLE:

LetBarrel Thickness = 60 mm Nominal Th. = 12.7 mmHeight of barrel = 50 mm

Then X = (60 tan 45 12.7) = (60-12.7) = 47.3 mm SoH1 = H + X + Z = 50 + 47.3 + 50 = 147.3 mm

Calculation of L

L = H1 + Shell Thickness = 147.3 + 20 = 167.3 mm

Note:Always take R as shell radius for nozzles attached with shell and write down single curvature in remarks.In case of the nozzles attached to head, R is taken according to the formula given below and write down double curvature in remarks. As shown in the figure below.

For Radial Nozzle:

R = 0.9 DFor Hillside nozzles at knuckle of head:

R = 0.17D

Where D is the inner Dia of vessel.

Further note that this rule is for Ellipsoidal head only

INTERPRETATION FROM ARAMCO FOR SELF RE-INFORCED NOZZLES

These nozzles do not require any external re-inforcement in order to make them strong enough to withstand stresses and moments. In other words we can say that these are the nozzles that do not require any pad e.g long welded neck and contour nozzles (type 9).

1. Contour nozzles may be designed with lips or without lips according to the requirements by ARAMCO standards.

2. In ARAMCO either JERMS or SAMSS standards, under following conditions, contour nozzles with lips or without lips are required.

Cyclic condition Equipment in thermal choc(NO CONTOUR REQUIRED)

Thick wall vessel with thickness 50 mm & greater Low alloy steel vessel with thickness 25 mm or greater(SUBJECTED TO QUERY REPLY)

Nozzles opening of 900 mm with design temperature of > 400 C(NO CONTOUR REQUIRED)

Vessel with design Temperature > 370 C(NO CONTOUR REQUIRED)

Vessel with design Temperature < -45 C(NO CONTOUR REQUIRED)

Lethal service Vessel with design pressure > 0.7 MPa (70 bar) Flange rating 600 # or greater except for CS material in non-cyclic condition For CS vessel with flange rating 900 # or greater Hydrogen service Severe wet H2S

Different sketches for self re-inforced nozzles (contour or LWN), with or without lips has been shown above.

INSULATION

Insulation must be added with vessel according to client requirements. If no any information is provided by the client in data sheet or material requisition then use the following parameters for insulation.

NORMAL CASES:

Thickness = 38 mm ; = 150 kg / m ;Spacing = 200 mm

Weight = 150 kg

SEVERE CASES:

Thickness = 40mm ; = 250 kg / m ;Spacing = 100 mm

Weight = 150 kg

ADDITION OF BEDS

If mesh is of stainless steel then its approximately density is calculated as follows (As a thumb rule)

Ass.s = 7880 kg / m

So(mesh) s.s = 7880 / 3 = 2600 kg / m

Liquid holdup = 30 % (Approx.)

Note:In case of beds addition in Compress, always mark only on Present when vessel is empty & include in lift weight

Important:We can also add bed in terms of vertical load. If the vessel is having three beds (N beds) then we have to add vertical load (w kg given). For this Purpose divide the vertical load w by N then add this load at the mid of each bed.

For packed beds always assume density equal to 2000 kg / m3 (i.e two times of water). This is considered only when density is not given by client.

EXAMPLE:

No of beds = 3Total vertical load = 2000 kgThen Load / each bed = 2000 / 3 = 666.7 kg = 700 kg (Approx.)

Mark only Present when vessel is empty & include in lift weight)

CALCULATIONS OF BED ON COMPRESS

Bottom of bed5050 mm(Variable)Bed depth6000 mm(Variable)Bed Diameter1900 mm(Variable)Bed Density901 kg / m3(Variable)

Liquid Hold up20%(Fixed) if not given in data sheetPresent when vessel is emptyInclude in lift weight

STIFFENING RINGS

Stiffening rings are added only when vessel wall thickness governs at external pressure

WIND & SEISMIC

FOR WIND:

SABIC always demands natural frequency for both wind and seismic as 1.00 or greater. So if H/D ratio of a column is more than 15 then always choose natural frequency as 1.00 for SABIC related jobs. ASCE 7.05 is selected if not given by client Normally take basic wind speed as 155 km / hr (40 m / s) Importance factor is taken as I = 1.15 Exposure = C Wind direction factor (Kd) = 0.95see table 6.4 (page-80) Topographic factor (Kzt) = 1 Un-mark / de-select No wind shear below support in compress Mark / select limit top deflection to 5mm for tall vessels having H/D ratio more than 15.

Note:Normally client mentions the wind code to be followed and its other specifications. If no any information is given then assume the above values and also see SAES-A-112 (ARAMCO standard for wind & seismic) and select values according to thearea where vessel is required to be installed.

FOR SEISMIC:

If no any code is given then choose UBC 1997 (building mounted) Mark / select the following points while designing on compressConsider vertical acceleration force multiplier = 0.3333Min. weight multiplier = 0.2

UBC- seismic code inputsZone = 1Importance factor = 1.25Soil Profile = SDRp factor (table 16-0) = 3H x / hr (eqn. 32.2)=1Amplification factor ap =1 Take seismic data of Berri equivalent to Jubail (SAES-A-112)

Note:It is recommended that always use standards for wind & Seismic according to the Client and area where vessel is required to be installed and try to avoid the use ofapproximate values.

PLAT FORMS & LADDERS

Thumb rule to put plate forms is to install them after every 6m height. Normally while designing platforms & ladders use the following scheme.

PLATE FORM # 1

Platform start angle=0Platform end angle=360(worst case and can be changed)Ladder angle=0(Depends upon the situation)Platform width=1200 mm(Normally fixed)Platform to datum=0.00 mm(Variable for 2nd platform & ahead)Shell clearance=152.4 mmGrating Weight=150 kg / m(Worst case fix)Railing weight=491 N / m(50 kg / m)(Worst case fix)Ladder start to datum=-4200 mm(Variable for 2nd platform & ahead)Ladder weight=981 N / m(100 kg / m)(Worst case fix)

Mark / check calculate & apply wind load Wind force co-efficient (Cf)= 2 Railing height= 1066.8 m Mark / check present when vessel is empty Mark / check Include in lift weight

PLATE FORM # 2

Platform start angle=0Platform end angle=360(worst case and can be changed)Ladder angle=90(Depends upon the situation)Platform width=1200 mm(Normally fixed)Platform to datum=6600 mm(Variable for 2nd platform & ahead)Shell clearance=152.4 mmGrating Weight=150 kg / m(Worst case fix)Railing weight=491 N / m(50 kg / m)(Worst case fix)Ladder start to datum=100 mm(Variable for 2nd platform & ahead)Ladder weight=981 N / m(100 kg / m)(Worst case fix)

Mark / check calculate & apply wind load Wind force co-efficient (Cf)= 2 Railing height= 1066.8 m Mark / check present when vessel is empty Mark / check Include in lift weight

TOP PLATE FORM

Platform length (l)=2000 mm(depends upon Dia of vessel)Platform width (w)=2000 mm(depends upon Dia of vessel)Platform angle=90(Depends upon the situation)Offset=1000 mm(Variable)Platform to datum=13400 mm(Variable according to vessel height)Grating Weight=150 kg / m(Worst case fix)Railing weight=491 N / m(50 kg / m)(Worst case fix)Ladder start to datum=6700 mm(Variable according to vessel height)Ladder weight=981 N / m(100 kg / m)(Worst case fix)

Mark / check calculate & apply wind load Wind force co-efficient (Cf)= 2 Railing height= 1066.8 m Mark / check present when vessel is empty Mark / check Include in lift weight

DESIGN OF BOOTS

The distance mentioned from tangent of boot must be added in the half of the dia of pressure vessel (in case of horizontal vessels) in order to determine the projection length of boot while designing a vessel on compress. As shown in the figure below.

DESIGN OF FLANGES

It must be noted that flange inside dia and pipe (nozzle) outside dia must be same. Since flanges are available in standard sizes and pipes ID can be made according to the flange ID requirements. As shown in the figure below.

GENERAL NOTES ABOUT DATA SHEET

Data sheet always supersedes specifications If some contradiction occurs between data sheet & code then consult with client. If no external design conditions are given then assume the following.0 kpa @ 60C If there is a requirement of full R.T (for ARAMCO) then whatever the thickness comes, there would be requirement of self re-inforced nozzles.

It means if shell thickness is 13mm at spot RT but clients requirement is full R.T due to service. Then say by checking full RT on compress, the thickness comes as 10 mm, then although the thickness is very small but due to Full RT according to ARAMCO standards, the designer would be intended to use self reinforced nozzles.

CALCULATIONS ON PV-ELITE

While adding saddles to horizontal vessel, dont forget to change dimension A (which is calculated from nearest tangent line) known as distance of saddle from node. In order to design a vessel on ASME Sec VIII Div 2.0, first change the code from Div 1.0 to Div 2.0 then go to configuration and uncheck ASME 2004, Ad-06. We will automatically move towards Div 2.0 Ed-2007, A-08. We cannot add more than four saddles with horizontal vessel in PV-ELITE. If vessel is very long say (80m or 100m), then divide the vessel into equal parts and determine saddle design and suggest number of saddles for each part of vessel separately. Always remember that whenever the material allowable stress is required to be enter in PV-ELITE, then put allowable stress value according to the design temperature of the part following SEC II part D. Whenever the allowable stress value of a non-pressure part is required to be enter in the software then always calculate it by the following formula

Allowable stress value2/3 x (yield strength of material)Fro non-pressure part

Number of nodes to be selected are always described as mentioned below

Head # 110 to 20Cylinder20 to 30Head # 230 to 40

If there are more than one cylinders then nodes are selected accordingly. For example lets suppose there are three cylinders then the order of selecting the nodes would be

Head # 110 to 20Cylinder # 120 to 30Cylinder # 230 to 40Cylinder # 340 to 50Head # 250 to 60

Orientation of vessel is selected by the following command.

Tools----->Flip model orientation

Units are selected by the following command

Tools----->Change Units

Code is selected from the option code given at the top of the pv-elite environment. Before starting 3D modeling on PV-Elite, always put the designed parameters in Design Constraints tab as a default settings then start modeling. Fundamental concept of PV-Elite fro modeling a vessel is that in PV-Elite, firstly we have to put value of thickness (assumed) by our perception. Then after running the software for code calculations, we have to further decide that whether the thickness is required to be reduced or increased or to be unchanged. Similarly if there is a requirement of stiffener ring then always put stiffener ring first and then calculate the required thickness. For selection of thickness, always remember the following rule.

For head ------ Finished thickness is not equal to nominal thickness (Nominal Th. = 1.15 x Finished Th.)

For Shell ------ Finished thickness is equal to nominal thickness

In order to regain the following tabs in PV-Elite environment, then go to input and check all the required tabs.

General Input, heading, design Constraints, load calculations, wind data & Seismic data.

For hemi spherical head there is no straight flange length. For ellipsoidal head, check/select the straight flange length as 50 mm. Always remember that while modeling a vessel with hemi-head in PV-Elite or compress, increase the length of the cylinder to about 100 mm than actual length of shell for welding provision. For stiffener rings, the following rule is followed

Ring fillet weld leg size = 0.707 x Thickness of ring section attached to vessel

For Aramco jobs, toe to toe distance between every pressure part should be atleast 20mm e.g stiffener ring wear plate and saddle etc. For applying Nozzle loads on WRC-297, use the following link

Input---------->Component analysis data

PV-ELITE WARNINGS

Warning # 1Unity check on rib exceeds 1.0RemedyIncrease number of ribs, rib thickness or web thickness.

Warning # 2One or more saddle stress exceeds its allowableRemedyIncrease number of saddles.