REPORT ON

20” CLASS 600 SWING CHECK VALVE

Visit to Indian Farmers Fertiliser Cooperative Limited (IFFCO)

Visit Date: 02.05.2014

PREPARED FOR: Indian Farmers Fertiliser Cooperative Limited

BACKGROUND:

L&T Valves supplied 3 Nos. of 20” class 600 swing check valve to IFFCO in the year 2007 vide

purchase order no. LOI/PNMM/4254.57/e/6701/ICB/AONLA I.

IFFCO had reported failure of 20” Class 600 swing check valve disc installed next to booster

pump P 1307 A at AONLA site. First failure of the disc happened on April 2011 and that was replaced

with new disc which also had failed recently. L&T Valves was asked to investigate the repeated failure

of the disc portion. Subsequent to this, Maswood Ahmed (Design) and Mr. Babuliji (Sales) visited IFFCO-

AONLA plant on 02.05.2014.

FLOW PARAMETERS:

The following are the actual flow parameters of the IFFCO-AONLA site,

Fluid Medium : Semi lean GV solution

Flow Rate : 1600 m3/hr

Pressure : 5.9 kg/cm2

Operating temperature : 110 °C

OBSERVATIONS:

• The disc stud portion which holds disc & hinge assembly had failed and there is no trace of nut.

Observed that the failed disc had slanted on the seat ring side causing obstruction to the flow.

• The 20” Class 600 check valve has been installed between pump and control valve. It was

understood from IFFCO that earlier 12” class 600 check valve was used in that line and later it was

replaced with AIL make 20” Class 600 check valve.

Disc Failed Portion

• However while changing the valve size, the size of the discharge pipe from the pump was still

maintained as 12”. Enlarger was used to connect the valve with pump discharge pipeline.

• The 20” class 600 check valve was installed right next to pipe bend and enlarger as shown below.

Actual site view

Pipeline Water Model

ANALYSIS:

1. For the given flow parameters, it is observed that for the 20” check valve disc does not open fully.

As a recommended practice, swing check valve disc has to open fully for minimum flow rate

irrespective of the line size. Hence for the given flow, valve size needs to be smaller.

20” Class 600 Swing

Check Valve

Enlarger

Pipe bend

Pump discharge

pipeline

Inlet to

Check Valve

Pump

Outlet

2. It is observed that the distance between pipe bend and swing check valve is very short. As a piping

design practice, swing check valves shall be installed at adequate distance from pipe bend /

elbows for uniform flow at the inlet of the check valve and to avoid turbulence flow.

3. Flow analysis was carried out on the CFX software considering the actual site condition and flow

parameters. The following points observed,

� Flow at the pump outlet is uniform and flow get disturbed and reaches to maximum velocity

at the pipe bend portion.

� In addition, the flow becomes further non-uniform because of the enlarger after pipe bend.

� Finally at the inlet of the check valve, flow is non-uniform and velocity variation found to be

very high. Also it is observed that the flow concentration is on one side of the disc portion.

L&T Valves analyzed this non-uniform flow acting on the disc surface as another cause for the failure

of disc portion.

CONCLUSION:

Based on the analysis, it is observed that the non-uniform flow at the inlet of check valve due to

existing pipeline design is cause for the repeated failure of the disc. Also, for the given flow, valve size

need to be smaller to make sure that the disc is in open condition for the minimum flow. Further

analysis on piping design and valve size shall be carried out by customer.