21st May 2024

Should filter housings conform to ASME BPE for critical processes?


What is ASME BPE?

ASME BPE is the American Society of Mechanical Engineers’ Bioprocessing Equipment standard. It was introduced in 1997 in response to biopharmaceutical production issues, such as inconsistent equipment cleanliness.

ASME BPE is relevant to industries with critical sanitary requirements, such as:

  • Biopharmaceutical
  • Pharmaceutical (API and cosmetic production)
  • Food and beverage

There are rules for every aspect of process equipment production. The society updates the standard regularly to include new materials and fabrication techniques.


ASME BPE and process filter housings

Reputable manufacturers make a range of ASME BPE-compliant sanitary filter housings alongside other hygienic housings. BPE-compliant housings are more affordable than they once were but are more expensive than non-hygienic and hygienic housing. That’s because they require more skill and higher-quality materials to make.

Need advice on ASME BPE compliance and filter technology? Get support from a filter expert.

What makes a filter housing hygienic?

1. Design features

Hygienic filter housings have:

  • Sanitary body closures and couplings
  • Sloped surfaces for effective draining (see image)
  • Components you can clean in-situ between batches
  • A wetted surface finish of SF4 (0.38Ra). This is better than standard hygienic surface finishes, which range between 0.4 and 0.8 Ra

cross section showing slope to aid drainage

2. Construction materials

The construction material must be appropriate for the application. This reduces the risk of pitting corrosion and chloride stress cracking or rouging.

 For example, manufacturers typically use 1.4435 stainless steel for its increased resistance to corrosion from high-purity water and steam. Our 76C & 72C range of sanitary housings conforming use this type of steel. But, if you’re looking for a material that holds up in high temperatures and against concentrated solvents like hydrochloric acid, a nickel-based alloy-22 resists corrosion more effectively. 

Elastomeric seals and O-rings need relevant FDA 21CFR 177 and USP Class VI approvals, too.

3. Material certification and traceability

All BPE-grade housings should have documentation linking wetted and pressure-retaining parts to the original mill 3.1 certificates. Component parts come with clear identification marks that aren’t always visible on finished housings. That’s why the paperwork is crucial for quality assurance and traceability.


4. Fabrication

Stainless steel grades such as 1.4435 only confer increased corrosion resistance if the welding is tightly controlled to limit ferrite (<3%) in the heat-affected areas. 

Because of the specific limit on ferrite, manufacturers need new weld procedures for automated and manual welding. This requires third parties to write and approve specific weld procedures, and the upskilling and approval of welders. Manufacturers should also measure and document ferrite levels to ensure they remain in the acceptable range.

Housing should allow as much automated welding as possible. The geometric design should allow welds to be fully ground to maintain the final specified surface finish.

It’s all about risk

Unsurprisingly, the additional paperwork, specific materials, and testing increases build costs. Housings conforming to BPE typically cost at least 50% more than standard spec pharma housings, and this is without factoring in premium materials such as Alloy-22.

So, are ASME BPE-compliant housings worth it? This depends on what the financial and quality implications are in your process. Moving to a housing conforming to BPE lowers the risk of process contamination from by-products caused by corrosion or batch-to-batch cleaning failures.

At Amazon Filters, we supply a range of single-stack filter housings that conform to ASME BPE. It may be more appropriate to choose certain aspects of the BPE standard to protect your process while minimising expenditure on capital equipment.

To discuss the ideal specification for your process, talk with our technical experts today.


Sign-up to our newsletter for the latest news and information straight to your inbox.