Process & Cleaning.

A valve does not clean itself. It either permits cleaning or prevents it, and which one comes down to geometry and to how the valve was installed rather than to anything printed on the certificate.

CIP and SIP, and whose problem they are

Clean in place circulates cleaning solution through an assembled system. Steam in place follows with saturated steam to sterilize it. Neither is something a valve does; both are something a system does to a valve.

Which is why cleaning chemistry is the plant's decision, not the valve maker's. Every facility runs its own agents and concentrations, and the practical question is whether those are compatible with the wetted materials: 316L for the body, and whichever compound the diaphragm is.

What the valve owes the cycle is geometry. No stem in the product, no packing crevice, a bore that drains, and a sealing surface that does not trap.

What a cycle actually does to a valve

Steam and hot caustic are hard on the parts that are meant to be soft.

• The diaphragm ages. It is the wear item, and cycle count plus temperature plus chemistry set its life. The body and bonnet outlast many of them.
• Bolted joints move. Steam then cold buffer expands and contracts the bonnet every cycle, which is how ordinary bolted joints work loose and start to weep.
• Compression drifts. A diaphragm that was over-compressed on assembly takes a permanent set faster under thermal cycling.

None of that is avoidable, which is why a diaphragm is a consumable and why hardware kits ship from stock. What is avoidable is uneven compression across it, which is what the Tork-Tite feet exist to prevent on a body sitting at its drain angle.

Dead legs are measured, not judged

A dead leg is a branch where flow does not reach, so cleaning solution does not exchange and soil sits. The convention is to express it as a ratio: the length of the unswept branch over the diameter of the run it comes off, L/D.

ASME BPE devotes a substantial section to this, in part SD, and sets out the acceptable ratios for different service. It is worth reading rather than estimating, because the answer changes with the application. For food, dairy and beverage installations the equivalent ground is covered by 3-A Sanitary Standards, and a line built to satisfy one is not automatically acceptable under the other.

Practically, a dead leg is designed out at the point the branch is specified. This is a large part of why point-of-use and zero-static bodies exist, and why a block body with the flow paths machined in behaves differently from the same arrangement fabricated from separate valves.

Drainability is the one you can get wrong on site

Every other item on this page is settled at design. Drainability is settled by whoever installs the valve.

A hygienic diaphragm body only self-drains if it is rotated so the bore falls continuously toward the outlet, and the angle depends on nominal size: 41° at ¼″, 30° at ⅜″, 25° at ½″, 18° at ¾″. Aquasyn etches the drain angle on the body so the installer is not guessing.

What to tell engineering

The cleaning cycle is the part of the specification most often left out of an enquiry, and it is the part that decides the diaphragm.

• Cleaning agent and concentration, and the temperature it runs at.
• Whether the line is steamed, and at what temperature and duration.
• Expected cycles per day or per campaign.
• The process fluid, and whether its compatibility changes with temperature or shear.

Compatibility at ambient is not compatibility at 250 °F, which is the single most common reason a correctly chosen compound fails early.