1、PFI Standard ES-5 | Denotes Revision (Revised December 2013) CLEANING OF FABRICATED PIPING Prepared by Pipe Fabrication Institute Engineering Committee All PFI Standards are advisory only. There is no agreement to adhere to any PFI Standard and their use by anyone is entirely voluntary. Copyright by
2、 PIPE FABRICATION INSTITUTE Dedicated to Technical Advancements and Standardization in the Pipe Fabrication Industry Since 1913 USA 511 Avenue of Americas, # 601 New York, NY 10011 CANADA 655, 32ndAvenue, # 201 Lachine, QC H8T 3G6 WEB SITE www.pfi-institute.org PFI Standard ES-5 | Denotes Revision (
3、Revised December 2013) CLEANING OF FABRICATED PIPING 1. Scope This standard describes methods normally used to clean fabricated pipe assemblies, the limitations of the methods and results to be expected. This standard defines two levels of cleaning. Unless stated otherwise, the standard level of cle
4、aning will be provided. 2. Selection of Cleaning Method 2.1 General The need for and degree of cleanliness on fabricated piping assemblies are dictated by the system requirements, the degree to which the system can be cleaned after installation and the need for removal of contaminants picked up duri
5、ng fabrication. Acceptance Criteria for various levels of cleanliness shall be a matter of prior agreement between the fabricator and purchaser. 2.2 Size and Configuration of Assembly In selecting a method of cleaning, the size and configuration of the part or assembly must be considered to permit v
6、isual examination of the interior and to allow complete drainage or removal of the cleaning materials. 3. Standard Cleaning Unless otherwise specified by the customer, cleaning will consist of removing all non- adhering material such as loose scale, sand, weld spatter particles, rust, cutting chips,
7、 etc., from the inside of the piping assembly by any suitable means. This level of cleaning will allow the presence of mill scale, surface rust, and tightly adhered weld spatter. 4. Special Cleaning 4.1 General When a greater degree of cleanliness is required, either the cleaning process or the acce
8、ptance criteria should be outlined in the purchasers design specifications. In all cases, the method of cleaning and the acceptance standard will be a matter of agreement between the purchaser and fabricator. 4.2 Special Methods Ferritic Materials 4.2.1 Rotary Tools Rotary type (turbinizing) tools w
9、ill substantially remove most loosely adhering mill scale and a significant portion of very heavy rust. They will not remove tight mill scale, heat treatment scale, medium to fine rust or any pitting. This type of cleaning is limited to internal surfaces only. 4.2.2 Wire Brushing Steel wire brushing
10、 will remove medium to light rust, but will not remove tight mill or heat treatment scale. It is limited to readily accessible surfaces only. 4.2.3 Grinding Grinding will remove rust, tight scale, pits, etc. from readily accessible surfaces only. Appropriate care must be taken to avoid grinding belo
11、w the minimum allowable wall thickness. 4.2.4 Blasting The most common method for removal of tight mill or heat treatment scale is blasting with sand, steel shot, or grit. This is most effective in producing a bare metal surface. Both internal and external surfaces may be cleaned by this method, but
12、 proper cleaning of piping internals is limited by accessibility to blasting equipment. Care should be taken in establishing configuration of fabricated piping assemblies, which require internal blasting after fabrication so that all internal surfaces will be accessible to blasting equipment. See PF
13、I Standard ES-29 for a more thorough explanation of this cleaning method. 4.2.5 Pickling For pipe requiring internal cleanliness substantially equal to bare metal, pickling is an effective overall method of removing scale, rust, etc. However this method limits the configuration of fabricated piping
14、PFI Standard ES-5 | Denotes Revision (Revised December 2013) assemblies to the tank size available and the ability to get acid flow to internal surfaces. 4.3 Special Methods Austenitic Materials 4.3.1 Degreasing Generally stainless steel materials, which have not been subject to heat for forming or
15、bending, require only a degreasing operation. This may be accomplished by immersion in, or wiping with, a clean cloth saturated with a suitable solvent, or by steam degreasing as described in 4.3.4 below. 4.3.2 Pickling and Passivating For stainless steels, which have been heated for forming or bend
16、ing and subsequently given a solution heat treatment, or for solution heat-treated materials, which exhibit a rusted appearance due to some type of contact with ferritic materials, the most effective cleaning is a pickling and passivation. See ASTM A380 and A967 for recommended cleaning solutions. H
17、owever this method limits the configuration of fabricated piping assemblies to the tank size available and the ability to get acid flow to internal surfaces. 4.3.3 Blasting Scale or discoloration produced as a result of heating for bending or solution heat treatment may also be effectively removed b
18、y blasting with iron-free silica sand or new aluminum-oxide grit. (Reclaimed sand or grit usually contains scale particles, which will result in a rusted surface on exposure to water and is therefore not recommended). If localized rusting appears after blasting, the assembly may be passivated by swa
19、bbing with a solution of nitric acid at room temperature until the free iron is removed. Follow with a water rinse. 4.3.4 Steam Degreasing and Rinse Certain nuclear systems involving high level radioactive service may require not only scale removal, but removal of contaminants, particularly halogens
20、 and sulfur, both internally and externally. An effective means of accomplishing this objective is a combination of steam-detergent wash followed by a rinse with demineralized water. This is performed as follows: All surfaces of all assemblies will be steam cleaned using spray nozzles and chemical a
21、dditives such as tri-sodium phosphate with detergent. Nozzles will be passed along the pipe centerline throughout its entire length to the maximum extent practical. Demineralized water used in preparing the chemical solution for steam cleaning as well as for rinsing shall have a conductivity of not
22、more than 20.0 Micromhos/cm and a pH range between 6.0 and 8.0 or as agreed between the purchaser and fabricator. Internal and external surfaces of pipe spools will then be spray rinsed with cold demineralized water without chemical additives. Rinsing will be done using a spray nozzle to thoroughly
23、flush internal surfaces of the pipe until complete cleanliness to the specified acceptance standard is attained. After rinsing, spools will be tilted to insure complete drainage and left to “drip-dry“. 5. Acceptance Criteria 5.1 Visual In all cases, assemblies will be visually inspected to assure th
24、at the required degree of cleanliness has been attained. NOTE: Unless specifically noted as unacceptable in a customers specification, thin films of rust on stainless steels should not be a cause for rejection provided there is no visible evidence of corrosion pitting. 5.2 Testing of Water Rinse For
25、 certain nuclear applications the pipe assembly will be internally rinsed with water until the required acceptance level is attained. Acceptance may be based on : 1. pH range of effluent. 2. Conductivity of effluent. 3. Particle number and size in filter cloths. CURRENT INDEX OF 2014-2015 PFI STANDA
26、RDS A complete list of PFI members and available membership CHARTER MEMBERS CONTRACTOR MEMBERS ASSOCIATE MEMBERS AFFILIATE MEMBERS HONORARY MEMBERS Associate and Affiliate member contributors Walter Sperko Sperko Engineering Services, Inc. Greensboro, NC Thomas Warrelmann Victaulic Company of Americ
27、a Easton, PA Sheryl Michalak Welding Outlets, Inc. Houston, TX PFI Standards and Technical Bulletins are published to serve proven needs of the pipe fabricating industry at the design level and in actual shop operations. Hence, such needs are continually considered and reviewed by the Engineering Co
28、mmittee of the Pipe Fabrication Institute to provide recommended procedures, which have been demonstrated by collective experiences to fulfill requirements in a manner for Code compliance. However, as the PFI Standards are for minimum requirements the designer or fabricator always has the option of specifying supplementary conditions in the form of requirements beyond the scope of the PFI publications.
