STAINLESS STEEL SELF LOCKING COUNTER (PAL) NUTS DIN 7967

Self Locking Counter (PAL) Nuts DIN 7967 — A PAL nut is a two-piece self-locking assembly: a slotted spring-steel counter ring sits captively in a recess within the nut body, and as the nut is threaded onto the bolt, that ring binds against the thread, generating an all-metal prevailing-torque lock without any nylon insert at all. Because the locking element is a metal spring rather than a polymer, it holds its grip at temperatures and in chemical environments that would soften or degrade a nyloc insert, which is the main reason to reach for a PAL nut over a standard nylon-locking type — exhaust systems, industrial plant running hot, and chemically aggressive environments are typical territory. It's most often used as a secondary counter or jam nut fitted behind a primary nut, adding a mechanical lock to the joint, though it can also serve as a standalone thin self-locking nut in its own right where a low-profile, high-temperature locking fastener is needed. Like other prevailing-torque designs, it's reusable, but the locking effect gradually diminishes with repeated removal and refitting as the deformed thread section and spring ring wear, so a fresh nut is the safer specification for safety-critical joints after multiple reuses rather than relying on a well-worn part. Compared with Art.980, another all-metal locking option, the two achieve prevailing torque through different mechanisms — a spring-steel counter ring here versus a deformed thread section there — so while both solve the same heat and chemical-resistance problem as a nyloc, they aren't dimensionally identical and shouldn't be assumed interchangeable without checking. A2 stainless suits most general high-temperature or chemical-resistant applications where extreme conditions aren't in play; A4 is worth the extra cost where the environment is also corrosive as well as hot, such as chemical processing plant. Sizing follows the mating bolt's diameter, pitch, and grade as with any nut.

FAQs
Is a PAL nut interchangeable with Art.980?
Both are all-metal prevailing-torque designs solving the same heat and chemical-resistance problem as a nyloc, but they achieve the lock through different mechanisms and aren't guaranteed dimensionally identical, so they shouldn't be assumed interchangeable without checking the specific part.

Does a PAL nut need to be used together with a primary nut?
Not always — it's most commonly fitted as a secondary counter nut behind a primary fastener, but it can also function as a standalone thin self-locking nut where a low-profile, high-temperature lock is needed on its own.

Is a PAL nut reusable?
It can be reused, though as with all prevailing-torque nuts, repeated removal and refitting gradually reduces the locking effect as the deformed thread section wears.

Is DIN 7967 suitable for high-temperature applications?
Yes, because there is no nylon insert, it tolerates significantly higher temperatures than a standard nyloc nut, making it suitable for hot environments where nylon would fail, with the practical temperature limit set by the base material and finish rather than a polymer insert.