Shorten Piping Cleaning Cycle to Speed up Shipbuilding

Mao Weihua

Over recent years, with Chinese shipbuilding industry becoming bigger and stronger, manufacturers build a lot of ships and offshore engineering platforms every year, tonnage of ships built becomes increasingly larger, caliber of piping cleaned becomes increasingly larger, piping becomes increasingly larger, hence requirement for piping cleanness becomes increasingly higher.

According to the industry standard requirements, piping products posterior to installation onboard are subject to oil cleaning to clean up impurities generated from the production and assembly and remaining in the piping and can only be put into use after reaching certain cleanness,otherwise residual impurities in the piping may harm equipment in the course of equipment transshipment and will form oil stain and generate oil pipe clogging.

At present, the shipowner has raised oil requirement for the new ship oil conduit system, ships under construction by domestic ship manufacturers have difficulty in system oil injection, causing certain effect on production schedule.

Traditional Piping Cleaning Equipment Consumes Time and Energy

The shipowner has increasingly high requirements for piping cleanness,which is normally required to be NAS-1638 Class 8, up to NAS-1638 Class 6,and multiple repeated cleaning and filter is required, which raises the shipyard requirement for cleaning equipment conditions and performance. Some ship manufacturers request piping cleaning equipment to have high cleaning efficiency, low cleaning cost, automatic control of temperature, adjustable cleaning pressure, both energy efficient and environment-friendly.

Most of ship manufacturers still use traditional piping cleaning equipment, on the production workshop, hydraulic oil is used to clean ship piping, then assemble cleaned piping onboard, involving large area cleaning equipment, components are dispersed and combined, as a result,piping cleanness can generally reach NAS-1638 Class 9 only. In the course of piping cleaning, oil absorption, filter,heating, return, etc. are controlled in a fragmented way, featuring poor continuity, workplace disorder, oil liquid severely runs, drips, leaks, sump oil in the filter cannot be disposed, causing serious pollution and severe waste. In addition, filter core element of its metal woven mesh involves low filter precision and long cleaning time.

Market survey shows it takes 30-40d to finish one small and medium tonnage ship piping with traditional piping cleaning equipment operating 24h every day and a large amount of sump oil. For cleaning one 10000t ship piping, the traditional piping cleaning equipment will consume some 10t hydraulic oil and more than 10000kWh electric energy and more than RMB10000 filter consumable and over 300 man-hours,sump oil generated reaches 5t.

New Equipment Shortens Cleaning Time

When the shipbuilding market is warming up, ship delivery as scheduled and even ahead of schedule is very important for ship manufacturers to further dissolve market risk and strengthen shipbuilding profitability.A 30-40d pipe cleaning cycle makes ship manufacturers using traditional oil cleaning system suffer a lot.

Optimistic about huge market demand of domestic ship piping cleaning equipment, domestic manufacturers develop marine piping cleaning equipment. The new type YZ series pipe cleaning equipment manufactured by Nantong Sea Lion Ship Machinery Co Ltd obtained high-technology product certificate in 2008, identified as a project with technical innovation fund for small and medium enterprises established by the Ministry of Science and Technology in 2010, obtained one invention patent for“Pipe hydraulic cleaning equipment”,one utility model for “Hydraulic oil pipe cleaning pump station” and one utility model for “Filter parts for hydraulic oil pipe cleaning pump station”.

YZ series pipe cleaning equipment adopts macro-molecule filter paper colating and macro-molecule composite filter element fine filtration, equipped with positive and negative cleaning control valve, pipe cleaning can be done positively or negatively. Minimum granular size of pollutant intercepted and absorbed ≤5um, filter precision reaches at least NAS-1638 Class 5,with simple operation, filter element use cost is only 1/5 of traditional cleaning method cost. The equipment is provided with flow rate-pressure smart control, temperature smart control, no carbonization heating, hydraulic pulse among other smart devices, capable of integrated centralized operation of barge oil, oil pooling, cleaning, temperature control and waste oil collection. It has forward and reverse cleaning function,turning hydraulic system water hammer phenomenon generated from pipe cleaning into a boon, artificially producing proper hydraulic impact, thus shaking out oxide skin, welding slag, etc. on the inner wall of the pipe, with further shortened cleaning time. Data show compared with traditional equipment, YZ series pipe cleaning equipment substantially shortens equipment cleaning time, no more than 40h, no sump oil, low energy consumption, no pollution,andtechnical property of the product reaches international advanced level.

Prominent Advantages in Relation to Imported Product

Compared with overseas pals, YZ series pipe cleaning equipment has characteristics of excellent comprehensive properties and low price, very suitable for pipe cleaning of domestic large ship repair industry, especially ocean ship engineering equipment.

As far as prices are concerned,one set of completely configured YZ series pipe cleaning equipment price is about RMB300,000, only 1/4 of overseas pals, while Japanese imported similar equipment price is about RMB200,000.despite obvious price advantages,technical property of the equipment is no less than overseas pals, and time spent on cleaning a system is only half of overseas pals. YZ product flow rate is up to 3000L/min, operating pressure is up to 42MPa,compared with 400L/min as maximum cleaning flow rate of Japanese pal and operating pressure ≤40MP.

Core parts such as filter element of YZ series new type pipe hydraulic cleaning equipment are jointly developed and manufactured by domestic manufacturer and world top-class cleaning company, its service life depends on pipe pretreatment, the better pipe pretreatment,the longer service life of macromolecular filter element; given no good pretreatment,service life of macromolecular filter element is shorter. In cleaning one 10,000t marine piping, given good pipe pretreatment, one macromolecular filter element can clean 10 pipe systems, even if pipe pretreatment is on the average, one macromolecular filter element can clean about 5 pipe systems.

Over recent years, Nantong COSCO Kawasaki Shipbuilding Engineering Co Ltd, Jiannan Shipbuilding (Group)Co Ltd, Zhoushan COSCO Shipyard,Hudong Zhonghua Shipbuilding (Group)Co Ltd, China Shipping Industry Co Ltd,Shanghai Shipyard Shipbuilding Co Ltd,Shanghai Waigaoqiao Shipbuilding Co Ltd, Shanghai Jiannan Changxing Heavy Industry Co Ltd and other domestic large and medium shipyards have in succession applied home-made new type YZ pipe cleaning equipment with good results.

The 318000 dwt VLCCs H1376,H1377 and H1317 and 158000 dwt H1352 tailor-made one set of YZ hydraulic pipe cleaning pump station for oil cleaning of main engine fuel oil system, main generator fuel system, boiler fuel system main engine servo oil system of the above four ships. Through 6-month use, YZ hydraulic pipe cleaning pump station can meet the oil requirement of the oil conduct system, and made many improvements in better oil injection quality, shortened oil time than the former two types of oil equipment.

In cleaning the turbine lubricant system of H1352 ship, YZ hydraulic pipe pump station cleaning equipment started pumping oil at 11 on the morning of March 29, 2017, oil sample was taken for relevant test at 2 pm of March 30,2017, through almost 30h oil pumping,grain size reached NAS-1638 Class 7.In comparison, it will take more than one week for other type of oil pumping equipment to be used in relevant system oil pumping and reach corresponding filter precision cycle. For that purpose,the Machine Installation and Testing Department of Waigaoqiao Shipbuilding said: “YZ hydraulic pump station pipe cleaning equipment quality is reliable,all technical parameters can meet oil pumping of all ship types, and can be applied in subsequent oil pumping construction.”★