Étanchéité – Tubes Technologies

Orifice clamp joint: how to choose the diameter of the calibrated orifice plate

jpediteur — Fri, 23 Oct 2026 13:47:17 +0000

Orifice clamp joint: how to choose the diameter of the calibrated orifice plate

On a line of 2″ to 5 m³/h water, a 16.4 mm orifice creates 0.5 bar of pressure drop. Formula, table from 1″ to 3″, choice of model and adjustment on site: the method for dimensioning a clamp joint at Port without adjustment valve.

Par Jean-Philippe Pavard, ingénieur, Tubes TechnologiesPublié le à compléterLecture 8 min

the essential

A hole clamp joint is a tri-clamp joint which carries a drilled 316L stainless steel plate: it adjusts a flow to the joint plane, without valve or dead arm.
The diameter is calculated with the LISO 5167-2: Q = C × (π × D² / 4) × √(2ΔP / ρ(1 − β⁴)), C ≈ 0.61.
Order of magnitude: 21.8 mm for 0.5 bar in a 2″ tube at 1.5 m/s.
Eccentric plate for lines that must drain, conical for vertical pipes (up to 4″).
On site, in particular at the EPPI sampling points, the diameter is adjusted by successive drilling, starting from a small orifice.

One Orifice clamp seal is a tri-clamp sanitary seal in which is set a stainless steel plate pierced with a calibrated hole. The diameter of this hole fixes the pressure drop, therefore the flow rate, to the joint plane, without valve or additional tapping. On a line of 2″ to 5 m³/h water, a 16.4 mm orifice creates approximately 0.5 bar of permanent pressure drop.

All the sizing fits in this relationship between the flow rate, the targeted pressure drop and the orifice diameter. This article gives the formula, an array of diameters from 1″ to 3″ and the rules of choice of the model.

What is a hole plate in a clamp fitting for?

A hole plate creates a fixed restriction. Passing through the lorifice, the fluid accelerates, its pressure drops, then it partially goes downstream. The part that does not go up is the permanent pressure drop, that which regulates the flow.

In a pharmaceutical or biotech installation, the orifice clamp seal is used for four uses:

balance a loop Purified water or DEPPI: Limit the flow of a short branch to guarantee speed in long branches.
Maintain a back pressure on the loop return, so that the points of use remain powered.
Adjust the flow rate of a sample point DEPPI or purified water, the most common use on site, or limit the flow of a point of use or a rinsing circuit.
break During a sterilization phase (SIP) or cleaning in place (CIP) phase.

The interest compared to an adjustment valve: no valve body, no dead arm added, no drift setting. The plate mounts between two ferrules instead of a standard joint. The SD share of BPE lasme Also cite the orifice plates among the components of the hygienic systems.

The sizing formula

The flow that passes through a sharp-edged port follows Liso 5167-2:

Q = c × (π × d² / 4) × √(2 × Δp / (ρ × (1 − β⁴)))

Q: Volume flow, in m³/s;
C: discharge coefficient, about 0.61 for a thin, sharp-edged plate;
D: Hole diameter, in m;
Δp: pressure difference on either side of the orifice, in PA;
ρ: density of the fluid, in kg/m³ (998 for water at 20°C);
β: ratio d / d between the head diameter and the inside diameter of the tube.

The permanent pressure drop is lower than Δp, because part of the pressure recovers downstream. For β between 0.3 and 0.4, it is 82 to 90% of Δp. For β = 0.6, it drops to 63%.

For a first calculation, when β remains below 0.4, the term (1 − β⁴) is close to 1 and the formula is simplified:

d ≈ √( 4 × q / (π × c × √(2 × Δp / ρ)) )

Table: Door diameter according to tube and pressure drop

The table below gives the diameter for a speed of 1.5 m/s in the tube, a current value in purified water circuit and in CIP. Tubes with ASME BPE dimensions (1.65 mm thick), water at 20°C.

Tube (Ø ext. × ép.)	Ø intérieur	Débit à 1,5 m/s	Orifice pour 0,2 bar	Orifice pour 0,5 bar	Orifice pour 1 bar	Orifice pour 2 bar
1" (25,4 × 1,65)	22,1 mm	2,1 m³/h	12,2 mm	10,1 mm	8,7 mm	7,5 mm
1 1/2" (38,1 × 1,65)	34,8 mm	5,1 m³/h	19,2 mm	16,0 mm	13,7 mm	11,7 mm
2" (50,8 × 1,65)	47,5 mm	9,6 m³/h	26,2 mm	21,8 mm	18,8 mm	16,0 mm
3" (76,2 × 1,65)	72,9 mm	22,5 m³/h	40,2 mm	33,5 mm	28,8 mm	24,6 mm

Perte de charge permanente visée. Calcul selon l'équation de l'ISO 5167-2, coefficient de décharge 0,61. Ordre de grandeur, pas une valeur de projet.

two useful readings. Dividing the pressure drop by ten only gains a factor of 1.6 to 1.8 on the diameter: the header diameter varies as the fourth root of the pressure drop. And a 1 mm error when drilling a 10 mm orifice changes the pressure drop from 30 to 50%, because it varies as the reverse of power four of the diameter. The precision of the drilling matters more than that of the calculation.

Encrypted Example: Balancing an EPPI Loop Branch

A 2″ ASME BPE Tube Loop Branch (47.5 mm inner Ø) should be limited to 5 m³/h, with a permanent pressure drop of 0.5 bar.

Flow: 5 m³/h = 0.00139 m³/s.
First calculation with the simplified formula: d ≈ 16.9 mm, i.e. β = 0.36.
Correction of permanent pressure drop: at β = 0.36, it is 85% of ΔP. It is therefore necessary to aim Δp = 0.58 bar through the orifice.
Result: an orifice of 16.4 mm, β = 0.34.
Speed in lorifice: about 6.5 m/s, without any particular risk for cold water under a few bars.

For LEPPI at 80°C, the density drops to 972 kg/m³ and the diameter gap remains below 1%.

Full, pre-drilled or vertical plate: choose the model

Joint clamp à orifice : plaque pleine à percer (à gauche) et plaque prépercée excentrée (à droite).

The orifice clamp joint comes in three executions. The choice depends on the orientation of the line and when the diameter is frozen.

Modèle	Description	Quand le choisir
Plaque pleine non percée	Livrée sans trou, à percer après calcul	Le diamètre n'est pas encore figé, ou vous percez vous-même
Plaque plate prépercée concentrique	Alésage centré	Ligne sans contrainte de vidange
Plaque plate prépercée excentrée	Alésage en bas de veine	Ligne horizontale qui doit se vidanger sans rétention, par exemple un circuit CIP
Plaque verticale conique	Plaque conique orientée vers le bas	Conduite verticale : une plaque plate y retiendrait le liquide. Jusqu'au 4"

On an eccentric plate, the hole is drilled opposite the tongue. The tongue rises upwards, which places the lorifice at the bottom of the vein. The visual cue becomes an editing mark.

Materials, sizes and standards

Caractéristique	Valeur
Plaque	Inox 316L, électropolie en standard
Rugosité de plaque	0,8 µm à 0,38 µm électropolie (EP)
Joint	EPDM, FKM, silicone, PTFE ou Steam-Flon
Liaison joint / plaque	Élastomère lié en standard, joint amovible en option
Tailles	1/2" à 6", jusqu'au 4" pour le modèle vertical
Normes de raccord	DIN 32676 série A, série B (ISO 1127), série C (ASME BPE)
Conformité	FDA et USP Class VI
Options	Languette gravable au laser, service de perçage

The bonded joint is replaced with its plate in case of failure. The removable seal is justified when you drill the plates yourself: it avoids contaminating the elastomer during the machining.

The plate stiffens the joint: a clamp that is too tight or misaligned pipes damage it faster than a full joint. the compression is taken at the torque prescribed for the collar, and a Safx Safety Clamp Collar Avoids the accidental opening of a fitting that has a restriction.

Joint clamp with orifice or adjustment valve: the comparison

The orifice clamp seal and the adjustment valve meet the same need, limit a flow, but not with the same constraints. The choice depends above all on the stability of the target flow and the cleanability requirements of the line.

Critère	Joint clamp à orifice	Vanne de réglage à membrane
Débit	Fixe, défini par le diamètre d'orifice	Réglable en exploitation
Bras mort ajouté	Aucun : la plaque est au plan de joint	Corps de vanne et ses raccords
Dérive du réglage	Aucune, sauf usure de l'orifice	Possible après démontage ou maintenance
Encombrement	Épaisseur d'un joint	Corps de vanne, actionneur ou volant
Nettoyage CIP et SIP	Plaque lisse, 0,8 µm à 0,38 µm EP, drainable en version excentrée ou verticale	Membrane à qualifier, rétention possible selon l'orientation
Qualification	Un diamètre à documenter	Position de réglage à verrouiller et à vérifier
Changement de consigne	Remplacer le joint clamp à orifice	Tourner le volant

In practice, the orifice clamp joint is imposed on the loop branches and returns whose flow does not change. The valve remains necessary where the flow rate is to vary depending on the production. The two often combine: a valve to adjust during commissioning, then a calibrated orifice plate to freeze the adjustment obtained.

Commissioning on site: adjust the clamp joint with holes by successive holes

On site, the door diameter is most often adjusted by tests, in particular on the EPPI sampling points. The calculation gives the starting point, the test gives the final value: the actual pressure losses of the sampling valve, output and loop always move a little from the model.

The method consists of pre-drilling a small diameter orifice clamp joint, and then growing in stages to the desired flow rate, measured under the standard operating conditions.

Leave small. Drill a first plate, or order a pre-drilled calibrated orifice plate, at a diameter less than that given by the calculation. An orifice can always grow, never be reduced.
Measure in standard operating conditions : Routine EPPI loop pressure and temperature, sampling valve open as with actual sampling.
Enlarge in stages. If the flow rate is insufficient, drill back to the next higher drill and start the measurement again. The flow varies like the square of the diameter: going from 4.0 to 4.5 mm increases the flow by about 27%. 0.5 mm bearings are sufficient.
Freeze the validated diameter. When the target flow is reached, engrave the diameter on the tongue and record it in the sampling point file.
reproduce without trying again. Order the pre-drilled replacement hole clamp seals with a diameter validated, rather than drilling on site at each maintenance.

Each drilling is done outside the clean zone, followed by deburring and cleaning the plate before reassembly. The removable joint is the right choice here: it is removed during machining and is not likely to be contaminated by chips. This method makes the setting reproducible: the same orifice clamp joint, reassembled after maintenance, restores the same flow rate at the sampling point.

Locate the plate once mounted

A port clamp seal cannot be seen, collar closed. This is the weak point of the solution: a plate forgotten during a maintenance, or reassembled in the wrong branch, unbalances the whole loop. The tab that protrudes from the fitting signals the in-line plate. Laser engraved with the header diameter, it allows you to check the correct plate without disassembling. it is the same logic as the Engraved clamp joint : travel information with the room.

Documents to download

PDFDimensions des joints clampCorrespondance collier, ferrule et tube, commune à toutes les exécutionsEN PDFListe de résistance chimique des élastomèresCompatibilité par fluide et par matière de jointEN

frequently asked questions

Qu'est-ce qu'un joint clamp à orifice ?

Engraved clamp seals: traceability that survives the bag

jpediteur — Thu, 15 Oct 2026 15:23:31 +0000

Étanchéité · Joints clamp Normes et surfaces

Engraved clamp seals: traceability that survives the bag

Two years of investigation for particles in a tank. Everyone knew what type of joint to look for. No one knew which one was up, nor from what lot he came from.

Par Jean-Philippe Pavard, ingénieur, Tubes TechnologiesPublié le 15/10/2026Lecture 11 min

the essential

Annex 1 of the GMP does not require engraving the joints: it requires proving control of each component in contact produced.
The label of the bag does not follow the joint once mounted: this is the weak link in traceability.
On request to order, the laser engraved clamp seal bears its batch number on the outer flange, excluding wet, legible tight collar and after SIP.
The FDA / USP Class VI certificate of the lot bears the same number: the proof travels with the part.
Engraving available in silicone, EPDM, FKM (Viton), PTFE and PTFE wrapped, depending on the manufacturer selected.

Annex 1 of GMPs does not require engraving a batch number on a clamp joint anywhere. It requires something else, more difficult: to be able to demonstrate, piece by piece, the mastery of everything related to the product. The engraved clamp joint is the easiest way to hold this requirement once the seal has left its bag.

The weak link: the label of the bag

Today, the traceability of a clamp joint is based on the label of its bag. As soon as the seal is taken out of the packaging and mounted on the installation, this documentary link is broken. The material certificate still exists. He no longer follows the room.

A sterile production site receives four to five inspections per year: ANSM, FDA, customers, internal audits. LANSM can happen without warning. The essential is played on the documents, and one day, the inspector’s finger falls on the maintenance of an EPPI loop.

A few dozen clamp joints, from 12.7 to 63.5 mm. PTFE, EPDM coated PTFE. SIPs at 121.1°C for 20 minutes, every week or every quarter depending on the loop. Simple question: this joint, which lot, which certificate, asked when?

The good news: the certificate exists. The worst: he sleeps in a binder, and the joint left his bag eight months ago.

what Annex 1 of the GMP really requires

The revised Annex 1 (“Manufacture of Sterile Medicines”) was published by the European Commission on August 25, 2022. It has been applied since August 25, 2023, and since August 25, 2024 for its item 8.123 on freeze dryers. In France, it constitutes the guideline LD.1 of the LANSM GMP Guide. The sterile production sites have been revising since their supplier requirements, in particular for elastomers in product contact.

The text is not about engraving. He talks about evidence. Five points directly affect the clamp joint:

Point de l'Annexe 1	Ce que dit le texte	Conséquence pour le joint clamp
2.3	Une stratégie de contrôle de la contamination (CCS) définit tous les points critiques de contrôle et l'efficacité des moyens de maîtrise.	Le joint en contact produit est un point critique : sa matière, sa conformité et sa durée de vie doivent être justifiées.
2.5	La CCS couvre notamment les équipements, l'agrément des fournisseurs de composants clés et la maintenance préventive.	Une fréquence de remplacement doit être définie et prouvée. Sans identification, impossible de savoir depuis quand un joint est en place.
3.2	Toute non-conformité fait l'objet d'une investigation ; l'inclusion ou l'exclusion de chaque lot doit être justifiée et enregistrée.	Un fragment de joint ou une fuite après SIP doit pouvoir être rattaché à son lot et à son certificat matière.
5.7	Une maintenance non planifiée sur un équipement critique pour la stérilité impose une évaluation d'impact enregistrée.	Le joint remplacé en urgence doit être identifié, comme celui qu'il remplace.
8.129	L'intégrité des composants des connexions aseptiques est assurée et documentée dans la CCS ; l'évaluation des fournisseurs inclut les modes de défaillance.	Le fournisseur de joints doit pouvoir documenter matière, lot et tenue en service.

Paraphrase du texte, d'après l'Annexe 1 des BPF (LD.1 du guide des BPF, ANSM).

what to remember

Annex 1 does not impose engraving as such. It requires demonstrating mastery of each element that can contaminate the product, and the joint in contact produced is one of them. The engraved joint clamp removes the weak link: dependence on a sachet or label that does not follow the part.

The cost of a joint that cannot be identified

At the first deviation, particles or a leak after SIP, the batch is blocked. Point 3.2 then becomes very concrete: it is necessary to justify in writing each lot included in the investigation or excluded from its scope.

Without a legible lot on the part, everything that has turned with “this type of joint” becomes suspicious. On a site that produces 5 to 6 lots per week, at €500,000 per lot, each week of production that cannot be excluded represents 2.5 to 3 million euros under investigation. Faced with this figure, the unit additional cost of an engraved clamp joint is negligible.

The CCS is the client who writes it. It is he who defends her before the inspector. as much as he has the proofs in hand.

The case of sterile ophthalmic products

An ophthalmic gel combines the factors that make individual joint traceability essential:

Mandatory sterility. The product is applied to the eye: any microbial or particulate contamination is a critical defect.
often aseptic production. A viscous gel is poorly filtered and often poorly supports terminal sterilization. Sterility is therefore based on sterilized equipment and their components, including seals.
repeated thermal cycles. Preparation tanks and transfer lines undergo frequent CIPs and SIPs, which age elastomers.
visible particles. A delastomer fragment in a transparent gel is detected at visual inspection and triggers an investigation.

For this type of site, an unidentifiable joint after assembly is a potential deviation during an inspection. The engraved clamp seal closes this door.

The engraved joint clamp: what is marked, where and how

At Tubes Technologies, the engraved clamp joint is an option: laser engraving of the batch number is asked when ordering, on the clamp FDA / USP Class VI clamp joints. It is not systematic. The marking does not make any material: neither ink nor label. It is placed on the outer collar, out of the fluid vein and out of the wet area, and remains legible once the collar is tight. It is due to SIP cycles. The certificate of conformity of the lot bears the same number: the proof travels with the part.

The proposed marked data: the manufacturer’s batch number, the material code (SIL, EPDM, PTFE, etc.) and the nominal size. A specific marking, for example the equipment marker, can be added at the customer’s request. The engraved material code replaces the color dot that some manufacturers use to identify the elastomer: a pellet reads badly, a text reads.

Sizes, engravable materials and marking contents vary from manufacturer to manufacturer. Depending on the ranges, the engraving covers the clamp joints from 1/2″ to 4″, i.e. tubes from 12.7 to 101.6 mm in outer diameter: the entire range of a current EPP loop. It applies to silicone, LEPDM, FKM, PTFE, Buna (NBR), PTFE / stainless steel composites such as seals tuf-steel and tuff-flex, and sometimes to orifice plates and sieves. Manufacturers announce a legible marking throughout the service life of the seal; Some also certify their ADI Free joints (without animal ingredient).

We work with several engraved clamp joint manufacturers: Dockweiler, Newman Sanitary Gasket, Rubber Fab and Techné. Our role: source the engraved joint clamp adapted to each site, according to its preferences (manufacturer already qualified, material, execution) and its regulatory requirements (FDA, USP Class VI, ADI Free, Annex 1 of GMPs). Several qualified sources also secure the supply.

Matière gravée	Exécution	Fiche produit
Silicone (platine)	Type I sans lèvre ou type II à lèvre de centrage, selon matière	Joint clamp silicone
EPDM	Type I ou type II selon matière	Joint clamp EPDM
FKM (Viton)	Type I ou type II selon matière	Joint clamp FKM
PTFE	Type I ou type II selon matière	Joint clamp PTFE
PTFE enveloppé (jaquette)	Selon matière	Joint clamp revêtu PTFE

the chain of traceability, from reception to replacement

An engraved clamp joint is only used if it is connected to the site’s quality system. The chain is in five links:

The engraved number Refers to the material and batch conformity certificate (FDA, USP Class VI).
at the reception, the site registers the lot in its quality system.
In assembly, the number is reported in the equipment register and the batch file.
in use, the SIP and autoclave cycles are counted by joint until replacement, which justifies preventive replacement.
In case of deviation, the batch of the joint in question is identified immediately, and the investigation perimeter is reduced by as much.

Mark without creating a new risk

Marking an engraved clamp seal should not create any new risk of contamination. Four points are to be justified, and each directly feeds the customer’s supplier qualification and CCS:

Point de contrôle	Exigence	Preuve à fournir
État de surface	Aucune altération de la face d'étanchéité ni de la face en contact produit	Plan de marquage, photo, contrôle visuel
Particules	Aucun résidu ni débris lié au marquage	Procédé sans encre ni étiquette, nettoyage après marquage
Extractibles / relargables	Profil inchangé par rapport au joint non marqué	Déclaration fabricant ou données d'essai
Conformité matière	FDA et USP Class VI maintenues	Certificat du lot reprenant le numéro gravé

Switch to engraved clamp joints: the 4-step method

Inventory The sizes, materials and annual quantities concerned, loop by loop.
Validate the content of the marking : lot alone, or lot + material + size, and specify the engraving option with each order.
Test A series of samples engraved with the associated type certificate, to validate the rendering before order.
Integrate the reference From the engraved joint clamp to the site supplier specifications and the CCS.

For elastomers and standard sealing, see also our article on theASME BPE (Part PM and Part MC).

Documents to download

PDFGuide de sélection des joints clampExemple de catalogue fabricant : gammes, matières, conformités FDA et USP Class VIEN PDFListe de résistance chimique des élastomèresCompatibilité par fluide et par matièreEN PDFFiche technique : dimensions des jointsCotes des joints clamp par tailleFR

frequently asked questions

L'Annexe 1 des BPF impose-t-elle de graver les joints clamp ?

Étanchéité – Tubes Technologies

Orifice clamp joint: how to choose the diameter of the calibrated orifice plate

Orifice clamp joint: how to choose the diameter of the calibrated orifice plate

the essential

Summary

What is a hole plate in a clamp fitting for?

The sizing formula

Table: Door diameter according to tube and pressure drop

Encrypted Example: Balancing an EPPI Loop Branch

Full, pre-drilled or vertical plate: choose the model

Materials, sizes and standards

Joint clamp with orifice or adjustment valve: the comparison

Commissioning on site: adjust the clamp joint with holes by successive holes

Locate the plate once mounted

Documents to download

frequently asked questions

Engraved clamp seals: traceability that survives the bag

Engraved clamp seals: traceability that survives the bag

the essential

Summary

The weak link: the label of the bag

what Annex 1 of the GMP really requires

what to remember

The cost of a joint that cannot be identified

The case of sterile ophthalmic products

The engraved joint clamp: what is marked, where and how

the chain of traceability, from reception to replacement

Mark without creating a new risk

Switch to engraved clamp joints: the 4-step method

Documents to download

frequently asked questions