SIST EN 4188:2004

• Abstract:

  This standard specifies the characteristics of elbows 90°, bulkhead, welded end, long, for pipe couplings 8°30', in titanium; alloy, for aerospace applications. ; Nominal pressure: up to 28 000 kPa; Temperature range: 55 °C to 135 °C

• Status: Published
• Publication Date: 30-Apr-2004
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: I08 - Imaginarni 08
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-May-2004
• Due Date: 01-May-2004
• Completion Date: 01-May-2004
• Ref Project: EN 4188:2001 - Aerospace series - Pipe coupling 8°30' in titanium alloy - Elbows 90° bulkhead, long, welded end

• Refers: SIST EN 3275:2019 - Aerospace series - Pipe coupling 8°30' up to 28 000 kPa Dynamic beam seal - Metric series - Technical specification
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3274:2011 - Aerospace series - Pipe coupling 8°30' - Thread end - Geometric configuration
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3311:2024 - Aerospace series - Titanium alloy TI-P64001 (Ti-6Al-4V) - Annealed - Bars for machining - D ≤ 300 mm - 900 MPa ≤ Rm ≤ 1 160 MPa
• Effective Date: 28-Jan-2026
• Refers: oSIST prEN 415-2:2022 - Safety of packaging machines - Part 2: Packaging machines for pre-formed rigid containers
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2656:2002 - Aerospace series - Pipe coupling - Coupling end, welded - Geometric configuration
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2491:2011 - Aerospace series - Molybdenum disulphide dry lubricants - Coating methods
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3312:2012 - Aerospace series - Titanium alloy Ti-6Al-4V - Annealed - Forgings De ≤ 150 mm
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2424:2008 - Aerospace series - Marking of aerospace products
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3267:2004 - Aerospace series - Washers, bulkhead, in titanium alloy
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4689:2012 - Aerospace series - Paints and varnishes - Two components cold curing polyurethane finish - High flexibility and chemical agent resistance for military application
• Effective Date: 28-Jan-2026

SIST EN 4188:2004 is the Slovenian adoption of EN 4188:2001 for aerospace pipe couplings in titanium alloy. It specifies 90° bulkhead elbows, long type, with welded end, for aerospace applications, including their dimensions, materials, surface treatment, marking and installation details.

What does SIST EN 4188:2004 specify?

SIST EN 4188:2004 specifies the characteristics of 90° bulkhead elbows, long, with welded end, for 8°30' pipe couplings in titanium alloy. It applies to aerospace fluid-system fittings rated up to 28 000 kPa and from 55 °C to 135 °C, so it is the document to use when selecting or checking this fitting type for pressure and temperature suitability.

The standard is organized into clauses on scope, normative references, required characteristics, designation, marking, technical specification and installation details. It also includes Figure 1 for configuration and dimensions, Table 1 for sizes and masses, and Figure 2 for installation details.

What are the key requirements of SIST EN 4188:2004?

SIST EN 4188:2004 ties the product definition to a specific geometry, material set and manufacturing condition. In practice, this means the buyer or manufacturer has a clear basis for selecting the correct elbow and verifying that it matches the aerospace series rules.

Geometry and dimensions

Clause 3.1 says the configuration, dimensions and mass are given in Figure 1 and Table 1. The dimensions apply before lubricating, and any dimensions not stated are left to the manufacturer only if the qualification and acceptance requirements of EN 3275 type II are met. That matters because it limits design freedom to features that do not affect qualified performance.

Surface condition

Clause 3.2 sets the surface roughness according to Figure 1 unless the design documentation says otherwise. Clause 3.5 adds an internal surface finish with a radius between 0.3 mm and 1.0 mm and a surface roughness of 0.8 µm, and it forbids hand deburring. In practice, this is about controlling flow, cleanliness and crack or burr risk.

Materials

Clause 3.3 specifies titanium alloy materials from EN 3311 or EN 3314, and from EN 3312 or EN 3315. These references point to the approved titanium alloy product forms for machining or forgings, so the standard keeps the material choice within defined aerospace-grade options.

Surface treatment and lubrication

Clause 3.4 states that the welded end has no surface treatment over at least 10 mm on the outside and bore diameters. It also requires lubrication to EN 2491 on threads and the sealing face, after abrasive blasting with non-metallic grit, with film thickness between 0.005 mm and 0.013 mm. This tells the manufacturer exactly how to prepare threaded and sealing areas for assembly.

Designation, marking and installation

Clause 4 gives the designation structure, including the optional code I9005 between the description block and the identity block. Clause 5 requires marking to EN 2424, style A and Figure 1. Clause 7 refers to Figure 2 for installation details, including the washer according to EN 3267 and the grip length relationship. These clauses matter because they support identification, traceability and correct assembly.

Technical specification and thread ends

Clause 6 points to EN 3275 type II for the technical specification, while EN 3274 covers the thread-end geometry and ISO 5855-3 covers MJ thread limit dimensions. That helps users check compatibility with the matching coupling system and thread form.

What terms does SIST EN 4188:2004 define?

• Bulkhead - a fitting arrangement intended for mounting through a partition or wall.
• Welded end - the end of the elbow prepared for welding to the pipe or assembly.
• 8°30' pipe coupling - the aerospace coupling family used by this standard, identified by the 8°30' form.
• MJ threads - the aerospace thread form used for the threaded ends, with limit dimensions given by ISO 5855-3.
• Type II - the EN 3275 technical specification category used for qualification and acceptance.
• Style A - the marking style required by EN 2424.
• TI-P64001 - the titanium alloy designation used in the referenced material standards.

Who uses SIST EN 4188:2004?

SIST EN 4188:2004 is used by aerospace designers, component manufacturers, inspection and quality teams, and buyers of fluid-system fittings. They use it to specify, make, check and receive 90° bulkhead elbows for aerospace pipe couplings in titanium alloy.

Which standards are used with SIST EN 4188:2004?

• ISO 5855-3 - gives MJ thread limit dimensions for fittings for fluid systems.
• EN 2424 - defines aerospace product marking.
• EN 2491 - covers molybdenum disulphide dry lubricant coating methods.
• EN 2656 - gives welded coupling-end geometric configuration.
• EN 3267 - covers bulkhead washers in titanium alloy.
• EN 3274 - gives thread-end geometric configuration for 8°30' pipe couplings.
• EN 3275 - provides the technical specification for 8°30' pipe couplings up to 28 000 kPa.
• EN 3311, EN 3312, EN 3314, EN 3315 - define the titanium alloy product forms used for manufacture.

What does the SIST EN 4188:2004 document contain?

The document contains a configuration drawing, a dimensional table and an installation figure. Figure 1 shows the elbow geometry, the marking area, the thread form reference and the across-flats dimension. Table 1 lists the code, thread size, several dimensions and the mass for each size. Figure 2 shows how the bulkhead elbow is installed with the washer, grip length and thread engagement relationship.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aerospace series - Pipe coupling 8°30' in titanium alloy - Elbows 90° bulkhead, long, welded endLuft- und Raumfahrt - Rohrverschraubung 8°30' aus Titanlegierung - Winkel-Schottverschraubungen 90° mit Anschweißende lange AusführungSérie aérospatiale - Systeme de raccordement 8°30' en alliage de titane - Raccords coudés a 90° pour traversée de cloison, type long a souderAerospace series - Pipe coupling 8°30' in titanium alloy - Elbows 90° bulkhead, long, welded end49.080Aerospace fluid systems and componentsICS:Ta slovenski standard je istoveten z:EN 4188:2001SIST EN 4188:2004en01-maj-2004SIST EN 4188:2004SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 4188October 2001ICS 49.080English versionAerospace series - Pipe coupling 8°30' in titanium alloy - Elbows90° bulkhead, long, welded endSérie aérospatiale - Système de raccordement 8°30' enalliage de titane - Raccords coudés à 90° pour traversée decloison, type long à souderLuft- und Raumfahrt - Rohrverschraubung 8°30' ausTitanlegierung - Winkel-Schottverschraubungen 90° mitAnschweißende lange AusführungThis European Standard was approved by CEN on 28 February 2001.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2001 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 4188:2001 ESIST EN 4188:2004

ScopeThis standard specifies the characteristics of elbows 90°, bulkhead, welded end, long, for pipe couplings 8°30', in titaniumalloy, for aerospace applications. Nominal pressure: up to 28 000 kPaTemperature range:
55 °C to 135 °C2
Normative referencesThis European Standard incorporates by dated or undated reference provisions from other publications. These normativereferences are cited at the appropriate places in the text and the publications are li
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