The True Cost of Poor Filter Housing Design

Product

Special Super Duplex Housing

Client

Global Oil & Gas Production Company

Application

Sulphate Reduction Membrane Protection

Location

Brazil

Value Added

Fit for Purpose Housing Design

Sector

Oil & Gas

Consequences of Poor Selection

Poor selection and specification of process capital equipment can have serious financial consequences. This is especially so within the Oil & Gas industry where premature failure of equipment can lead to eye-watering daily revenue loss.

When it comes to filtration systems, failure can occur in two major areas:

The Hardware (Filter Housing). Failure such as leaks under pressure / corrosion issues /ergonomic design
The Software (Filters). Failure due to incorrect sizing for flow and contamination levels/ fluid compatibility issues / not consistently performing to specification

In this case study we look at the importance of housing design. It is essential that the trouble-free operation of the filtration system is prioritised over the initial capital cost of the project.

The Problem

A redesign of the sea water guard filters protecting the Sulphate Reduction Membranes was required due to excessive pressure drops and low efficiency.

The new design consisted of two 64 round housings installed in parallel. This significantly reduced the differential pressure and ensured the filter performance and efficiency was maintained.

The new guard filter system ran well for the first year of operation. However, during routine filter changeout it was highlighted that certain areas of the housing were beginning to corrode. The consequence being that both housing had to be removed and replaced after just 18 months operation. This caused interruption in production and poor protection to the sulphate reduction membranes which subsequently required much more frequent CIP'ing to remain operational.

corrosion on Sulphate Reduction Protection filter housing 1-1

The Cause

When designing a filter housing that is going to be used in harsh environments such as offshore, there a couple of options when deciding how to best protect the housing from deterioration over time.

Use a lower cost carbon steel and apply a coating for protection
Design the housing using more costly but more resistant specification material such as Super Duplex Stainless Steel.

In this particular case the lower cost option of carbon steel and coating was chosen.

While a correctly specified and applied coating will give the protection required when new, operational conditions and housing detail design can fundamentally affect its longevity.

Housing Design

It is imperative that due consideration is given to the detailed design if the coating option is chosen. All corners should have generous radiuses, there should be no sharp edges. In this particular case there were several areas where corners did not have sufficient radii. The consequence of this is that the coating will not be the required thickness and can be easily damaged.

Filter Changeouts

The process of filter changeouts, especially in such large housings such as this, can result in damage to the coating from dropping fitting such as nuts / bolts onto the surface or the large circular retaining plate being allowed to drop onto the internal surface of the housing. In summary the housing will be subjected to physical abrasion during its lifetime purely for the process of filter changeouts.

The Solution

The two new 64 round housings were designed using Super Duplex Stainless Steel instead of relying on a secondary coating. This ensures a working life of at least 20 years, a vast improvement over the 18 months for the original coated housing.

They also feature Xylan 1424 fluoropolymer coating on the swing bolts to prevent galling, ensuring quick access for filter changeout.

The housing is filled with our highly efficient and high capacity SupaPleat HFC SRP specifically designed for the protect of sulphate reduction membranes.