CB/T 4558-2025 in English

VALID

J Class Flange Cast Iron Flow Observer

Issued on:2025-04-10
Implemented on:2025-11-01
File Format:PDF
Delivery:Via email within 1~3 business days

Price(USD)： $135.00
$131.00

Standard No:	CB/T 4558-2025
Document status:	VALID
Title in English:	J Class Flange Cast Iron Flow Observer
Title in Chinese:	J类法兰铸铁液流观察器
Language:	English
File Format:	Electronic (PDF)
Delivery:	Via email within 1~3 business days
Issued on:	2025-04-10
Implemented on:	2025-11-01
ICS Classification:	47.020.30-Piping systems
Chinese Classification:	U55-Marine pipe fittings
Professional Classification:	CB-Watercraft
Related Keywords:	j class flange cast iron flow observer introduction analysis face flange full plane flange improve sealing reliability inspection system basic requirements jis flange standards cast iron flange bolts

Introduction

Analysis of the core content of the standard

Technical indicators	CBM 1039-1981	CB/T 4558-2025	Improvement significance
Maximum working pressure	Unclear classification	0.5MPa(5K grade)	Adapt to the high pressure system of modern ships
Sealing surface type	Raised face flange	Full plane flange	Improve sealing reliability
Inspection system	Basic requirements only	Complete test methods + inspection rules	Standardization of quality control

Detailed explanation of key technical requirements

Material specifications

The body is made of HT200 grey cast iron, which must meet the tensile strength ≥ 200MPa requirement of GB/T 9439-2023; the lens uses tempered glass, and its impact resistance must pass GB 15763.2-2005 certification.

Structural innovation

The new full-plane flange design (see Figure 1) is matched with aramid rubber gaskets to achieve zero leakage under 0.55MPa sealing test pressure. The diameter of the perspective window increases with the increase of DN, and the nominal size of 20-200mm corresponds to the observation aperture of 20-200mm.

Implementation and application recommendations

Selection guide: Fuel pipelines are recommended to be DN50 or above, and lubricating oil systems are preferred to use DN32-DN65
Installation points: Flange bolts should be cross-tightened, and the torque should be controlled within ±10% of the JIS B2239 standard value
Maintenance cycle: It is recommended to check the aging of the gasket every 5000 hours

Standard evolution analysis

The main driving forces for this standard to replace the 1981 version are: the increase in the pressure level of ship power systems (from 0.3MPa to 0.5MPa), the popularization of asbestos-free sealing materials (in line with GB/T 22209-2021), and the need for international integration (adopting JIS flange standards).

More samples: JC/T 2453-2018 GB 50021-2001(2009) JGJ 94-2008

Sample only — not a preview of CB/T 4558-2025