SIST EN 4312:2009

SIST EN 4312:2009 is the Slovenian adoption of EN 4312:2006 for aerospace studs with a coarse tolerance reduced shank, medium length thread, in heat and corrosion resisting steel, with aluminium pigmented coating. It specifies the stud characteristics, designation, marking and technical specification for parts classified at 1 100 MPa at ambient temperature / 315 °C.

What does SIST EN 4312:2009 specify?

SIST EN 4312:2009 specifies the characteristics of the stud type named in its title and organizes them into six clauses: Scope, Normative references, Required characteristics, Designation, Marking and Technical specification. For a reader, that means the document is mainly a product-definition standard - it tells you what the stud shall be like, how to identify it, and what supporting standards apply.

What are the key requirements of SIST EN 4312:2009?

Geometry and dimensions

SIST EN 4312:2009 gives the stud configuration, dimensions and masses in Figure 1 and Tables 1 and 2. The dimensions and tolerances apply after coating, so the finished part has to be checked in its coated condition, not only before finishing.

The standard also points to ISO 7913 for tolerances of form and position. In practice, this is what keeps the fastener within aerospace fit and alignment limits when the stud is installed.

Materials, threads and surface treatment

SIST EN 4312:2009 requires heat and corrosion resisting steel with strength class 1 100 MPa, using TR 3775 for material selection. For thread geometry, it uses ISO 3353-1 for lead and runout threads and ISO 5855-2 for MJ thread limit dimensions.

Surface treatment is controlled by EN 4474 for aluminium pigmented coatings. The standard also allows optional lubrication with code E, which matters when ordering because the lubrication state has to be stated in the designation.

Designation, marking and procurement

SIST EN 4312:2009 defines a coded designation made up of a description block and an identity block. The code combines the standard number, hole code, diameter code, length code and lubrication code, so users can order the exact stud variant without writing a long free-text description.

Marking follows EN 2424, style C, with MJ and indented marking shown in Figure 1. For procurement and acceptance, clause 6 uses ISO 8168 as the technical basis, but manufacturer approval is handled through EN 9100 and stud qualification is not applicable under this standard.

What terms does SIST EN 4312:2009 define?

• MJ threads - The aerospace metric thread form used for these studs; the standard ties its limit dimensions to ISO 5855-2.
• Diameter code - The designation code that selects the stud diameter shown in Table 1.
• Length code - The designation code that selects the stud length shown in Table 2.
• Hole code - The designation code used when the stud includes the optional hole shown in Figure 1.
• Lubrication code - The designation code that identifies the lubrication state, including the optional lubrication linked to code E.
• Strength classification 1 100 MPa - The material strength level used for the stud classification and referenced in the scope and material clause.

Who uses SIST EN 4312:2009?

SIST EN 4312:2009 is used by aerospace fastener manufacturers, design engineers, procurement teams, inspectors and quality managers. They use it to select the correct stud variant, specify the coating and lubrication state, check dimensions and marking, and align purchasing and acceptance with the aerospace supply chain.

Which standards are used with SIST EN 4312:2009?

• ISO 3353-1 - Defines lead and runout threads for rolled external threads.
• ISO 5855-2 - Gives MJ thread limit dimensions for bolts and nuts.
• ISO 7913 - Sets tolerances of form and position for aerospace bolts and screws.
• ISO 8168 - Provides the procurement specification used as the basis for technical requirements.
• EN 2424 - Defines aerospace product marking.
• EN 4474 - Covers aluminium pigmented coating methods.
• EN 9100 - Supplies the quality management system requirements used for manufacturer approval.
• TR 3775 - Gives aerospace bolt and pin material guidance.

What does the SIST EN 4312:2009 document contain?

SIST EN 4312:2009 contains one dimensional figure, three tables and six clauses. Figure 1 shows the stud configuration and the optional hole, while Table 1 links diameter codes to the MJ thread sizes and related dimensions.

Table 2 links length codes to stud lengths and gives approximate masses for information. Table 3 gives the hole code used in the designation. The document also includes an example designation format, the marking rule and the technical specification basis for procurement and approval.