ISO 28522:2009

Ships and marine technology - Hydraulic oil systems - Guidance for assembly and flushing

ISO 28522:2009 provides guidance for assembly and flushing of hydraulic oil systems. The aim of the flushing process is twofold: to remove dirt from the erection, installation, and to demonstrate that the pipes and the system as a whole are sufficiently clean. ISO 28522:2009 gives guidelines to ensure that pipes and components are mounted and tested correctly. It also gives practical conditions for the flushing oil and filter.

Navires et technologie maritime — Les systèmes hydrauliques de pétrole — Directives pour assembler et rincer

General Information

• Status: Published
• Publication Date: 08-Feb-2009
• ICS: 47.020.99 - Other standards related to shipbuilding and marine structures
• Technical Committee: ISO/TC 8/SC 3 - Piping and machinery
• Drafting Committee: ISO/TC 8/SC 3 - Piping and machinery
• Current Stage: 9060 - Close of review
• Completion Date: 04-Mar-2030

Overview

ISO 28522:2009 - Ships and marine technology - Hydraulic oil systems - Guidance for assembly and flushing - provides practical guidance for assembling, flushing, testing and commissioning hydraulic oil pipework and components on ships. The standard’s primary objective is twofold: remove dirt introduced during erection and installation and demonstrate that pipes and the overall system meet required cleanliness levels before entering service.

Key topics and technical requirements

• Assembly checks
  • Verify blank-offs on pipes and components are undamaged; repeat cleaning if needed.
  • Blow through assembled pipework with dry high‑pressure air or nitrogen; lint‑free cloths may be pulled through pipes.
  • Leak tests with dry air and/or soap and water; components can be bypassed or blanked-off during testing.
• Shock testing
  • Pipe systems shall be shock tested a minimum of 25 cycles at the specified test pressure with components bypassed.
• Flushing procedure
  • Use a flush‑rig with the correct filter rated by beta ratio (β) - defined as (particles > x µm at filter intake) / (particles > x µm at filter discharge).
  • Connect equivalent pipe dimensions and flush separately to avoid pressure loss; circuits should be connected in series.
  • Bypass or blank off built‑in components during initial flushing; vibrating units may be used.
  • Maintain flush oil temperature at least equal to expected service temperature but not exceeding 60 °C (disposal max 80 °C).
  • Continue flushing until cleanliness criteria are met (see ISO 28521 for specific cleanliness tables and recommended flow velocities).
• Pressure testing
  • Conduct pressure tests (with components bypassed/blanked-off) to verify pipe strength and system integrity.
• Commissioning
  • Replace non‑system flushing oil with designated system oil (use a filter when filling).
  • Start pump units, manage breathing/refilling, set pressure regulating/relief valves, and invite supplier representative to verify cleanliness. Documentation of achieved cleanliness follows ISO 28521.

Practical applications and users

ISO 28522 is intended for shipbuilders, marine system integrators, naval architects, shipboard engineers, hydraulic technicians and maintenance crews responsible for:

• Commissioning new hydraulic systems on vessels and offshore units
• Overseeing installation quality and cleanliness verification
• Planning flushing and testing activities to minimize contamination-related failures

Related standards

• ISO 28521 (referenced throughout ISO 28522) - provides the detailed grades of cleanliness, flushing acceptance criteria and recommended flow velocities (listed as to be published in the ISO 28522 document).

Keywords: ISO 28522, hydraulic oil systems, flushing, marine hydraulic systems, assembly guidance, cleanliness, beta ratio, pressure testing, commissioning.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 28522
First edition
2009-02-15
Ships and marine technology —
Hydraulic oil systems — Guidance for
assembly and flushing
Navires et technologie maritime — Les systèmes hydrauliques de
pétrole — Directives pour assembler et rincer

Reference number
©
ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Recommended guidelines on assembly . 1
3.1 General. 1
3.2 Shock test. 2
4 Recommended guidelines for flushing . 2
5 Pressure testing. 2
6 Commissioning . 3

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
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International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 28522 was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee
SC 3, Piping and machinery.
iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 28522:2009(E)

Ships and marine technology — Hydraulic oil systems —
Guidance for assembly and flushing
1 Scope
This International Standard provides guidance for assembly and flushing of hydraulic oil systems. The aim of
the flushing process is twofold:
⎯ to remove dirt from the erection, installation, and
⎯ to demonstrate that the pipes and the system as a whole are sufficiently clea
...