Understanding Pressure Vessel Engineering Fabrication Drawings: A Detailed Guide

Understanding Fabrication and Engineering Drawings of a Pressure Vessel

 

Pressure Vessels are pivotal in industrial heat transfer applications. This blog post will guide you through the intricate details of reading and understanding the engineering drawings of these essential devices, focusing on Knockout Drum.

 

Components and Structure

Pressure Vessel consist of several key components: the shell, Dish ends, Inlet outlet Nozzles, Saddle leg supports, couplings. Each part plays a crucial role in the vessel and its overall functionality in system.

 

Reading the Engineering Drawing

Overview

The document shown above is an engineering drawing of a Knockout Drum.

Engineering drawings typically use multiple views to represent the object.

 

Let's begin by examining the drawing to extract key measurements and specifications.

 

Detailed Breakdown of this Pressure Vessel Drawing

Shell Dimensions

 

Length of Shell:  1500 mm [Excluding straight face 50 mm (SF) of both side dish ends] This is also called height of shell HOS.

Thickness of Shell: 10 mm [Shown in drawing along with diameter]

Diameter of Shell: 508 mm [Outside Diameter]

This is made with rolled plate with a development length is calculated by formula (mean diameter + thickness) x 3.142

= (OD – thickness x 3.142   = (508-10) x 3.142= 498 x 3.142= 1564.716 mm. In other words, is you roll the 10mm plate of 1564.716 mm length it will form an outside circle diameter of 508mm.

Material of Construction: SA 516 Gr 60 or 70 (shown in material chart of drawing sheet )

 

Dish Ends Dimensional Specifications

Type:- 2:1 Ellipsoidal dish end

Diameter (OD) of both dish:  508 mm [Same as shell outside diameter]

Thickness: 10 mm thk [Nominal 10 mm thk and min required thickness at knuckle 8 mm] At knuckle dish thickness decreases due to elongation by cold pressing operation while manufacturing. With help of D meter one can measure this thickness.

Material of Construction: SA516 Gr 70 shown in material chart.

 

Additional Details – Nozzle schedule chart shows:-

  

N1 & N2 - Gas -Inlet and Outlet Dimensions: Nozzle schedule chart shows oil Inlet and oil outlet 65NB Sch 40 pipe blanked. (Blanked nozzle pipe connections mean, it is closed with blind plate welded to end of pipe)  

N3 safely valve nozzle connection 40Nb Sch 80 pipe blanked.

N4 a/b level transmitter nozzle connection 40Nb Sch 80 pipe blanked.

N5 Pressure indicator nozzle connection 15Nb Sch 80 blanked.

N6 Oil heater nozzle connection 40Nb Sch 80 pipe with flange ANSI B16.5 class 300 SORF (slip on raised face) with counter flange, gasket and hardware/fasteners (hex bolt with nuts).

N7 Purge nozzle connection 20NB Sch 80 Blanked.

N8 Drain nozzle connection 20NB Sch 80 Blanked.

 

Orientation plan:-

Orientation plan shows orientation of the all nozzles, legs, supports, lifting hooks, on the pressure vessel on a degree scale of 0 degree to 270 degree by dividing vessels top view into 360 degree.

Nozzles N1 , N4A and N4B are on 0 degree.

First leg support is at 30 degrees. Second are third leg are 120 degrees apart from each one maintaining the 1100mm height of the vessel from ground zero.

Nozzle N8 is on 90 degree direction from bottom center of vessel with 200 mm standout and lifting hook Sr. no 11 is also in 90 deg.

N6 is at 180 degree and 65 mm below weld line (weld line is a joint of shell and dish end) in drawing it is shown as WL. Whereas TL is total length of the job.

Lifting hook item no 11 and third leg support is at 270 degrees.

N5 is at 270+45=315 degrees and 200 mm below top WL of vessel.

Nozzles N3 , N2 and N7 are on top dish end as shown.

Separate Supper elevation , end view , plan with leg plan section BB shows all necessary fabrication details of Leg supports

 

Bill of material chart shows all material of construction with required technical specification of all item number ( 9 to 32 )

 

Thickness chart shows all finish thickness of material to be used for all item number ( 9 to 20 )

 

Notes :- Sr. 1 to 12 are to read carefully before start of procurement and  manufacturing fabrication of vessels .

 

Design Data:

Design Code: ASME Sec VIII Division I , 2007 Edition.

Design Pressure: shell side 21 kg/cm2 (Gauge

Design Temperature: shell side  +120 and (-) 28 degree Celsius

Test Pressure: shell side 23.1 kg/cm2 (Pneumatic -by Dry Nitrogen)

Operating Fluid R717

Radiography: - Spot + T

Joint efficiency: - 0.85 (this indicates there is no need of 100% x ray for all the weld joints. You need to do 10% of spot radiography of total welding length and all T joints of shell if applicable and all shell to dish end T joints)

Inspection:- as per approved QAP ( “Quality assurance Plan” given by client along with work order)

 

Thanks for Reading!

Let me ask you one question for you from above drawing.😃

Why is the jacket of dotted outline is shown to vessel? what does it mean?

Give me your reply on comment section below!👇