16.5 Other Elements of Blueprints
Cameron Kjeldgaard
The Title Block
The title block is a ruled space, typically in the lower right corner of the print, that provides general information about the drawing. The formatting of title blocks is not standardized, though they all have the same general appearance, they may present different information, or the same information in a different location. It is important to review the title block when beginning any fabrication project, as they provide valuable information. The important elements in the title block are discussed below:
- The project name, may also appear as a job name or job number, is important when working in environments where several welding jobs are going on at once.
- The drawing title is very important, in place of a title a numeric or alpha-numerical identification number can be used. Be sure to check the drawing title or identification to ensure you are working on the correct project.
- A drawing number or sheet number is necessary when working with multiple page drawings.
- A revision number, or revision record, is abbreviated “REV” towards the bottom right corner in the title block above. In large, or long term, welding projects changes can occur while the job is in progress. The revision record keeps track of changes made to the drawing as a result. The above revision is 0, meaning this is the first issue of this drawing. If revisions have been issued be sure to use the most current revision.
- The scale of the drawing, if there is one, is provided in the title block. Drawings are not always to scale, if no scale is shown, or if you see the abbreviation NTS (Not To Scale) the drawing is not to scale. If a drawing is to scale then the size and proportions of the object as it is drawn relates to the object’s actual size. This relationship is written as a ratio. In the title block above the drawing is drawn in a 1:4 scale, this means every 1 unit of measure on the drawing will equal 4 units of measure on the real life object. Like the scale on a map this is a reduced scale, meaning the drawing is smaller than, but has a proportional relationship, to the actual object. In full scale drawings the object is shown on the print in the same size as the actual object. Drawings can also be on an enlarged scale for small detailed parts. An enlarged scale would be written like 4:1, if we reverse our earlier example. The quantity of measure on the drawing is always on the left side of the ratio, and the actual measurement on the right.
- The quantity of assemblies or weldments to be produced may also be shown in the title block, alternatively, it may be shown in the bill of material discussed in the next section.
- There is typically a space for general notes to be written in the title block. These notes may give general fabrication and welding requirements. These must be reviewed prior to fabrication to ensure all requirements are met. In the above example we can see a few fabrication and welding requirements in the upper left corner of the title block.
The Bill of Material
A bill of material, sometimes called a parts list, is usually located in the upper right corner of the drawing. Like the title block, the bill of material is not standardized. The above example is from structural drawing used to construct a building. A bill of material in the aerospace or pipeline industry may provide different information or present it in a different way. Below we’ll discuss information which is common to the bill of material across industries:
- A quantity of required assemblies and parts will be given. It should be noted that if multiple assemblies are required, the quantity of parts shown on the bill of materials is typically what will be needed to complete all assemblies.
- Part numbers, or mark numbers in the example above, are numeric or alpha-numeric identifications for individual parts. Part numbers are typically called out with leader lines on the base view of the drawing.
- A description of the part is usually present. This often includes the dimensions of the part, and a letter or symbol to indicate the shape. For plate and sheet parts the convention for listing its size is thickness X width X length. In the example above p18 (part number) has a description reading PL (designating plate) ⅜” (thickness) x 4 ½“ (width) and a length of 1’ – 6” listed in a separate column. Metal products are produced in many shapes, various styles of I-beam, angle, pipe, square tubing, and so on. Each of these shapes is produced in many sizes and have common conventions for listing their dimensions. The American Institute of Steel Construction has a library of shapes available called The Structural Steel Dimensioning Tool.
- A column for remarks or notes may be provided. This is used to provide any type of specific information about the part, such as if it is bent or shaped in some way, or requires a special paint or coating.
Notes and Specifications
Any written information on a drawing may be considered a note or specification. It is important to review all notes and specifications before beginning any fabrication project. It is easy to become overwhelmed by the complex drawing and number of dimensions on some prints, glossing over written notes. Notes and specifications inform you of important requirements, missing them can result in a huge amount of rework.
Notes may be general or local. Local notes are given on leader lines and apply to specific parts or features. The hole dimensions discussed in Hole Dimensions and Specifications in Section 16.4 are examples of local notes. Welding symbols, which are discussed in detail later, are also an example of a local note.
General notes apply to the entire assembly detailed on the print. General notes will usually appear in a ruled out area in the title block. Other times general notes might be placed in any free paper space on the drawing. General notes on a print are subject to exception. A general note may read “all holes to be ¾” diameter UNO”, this note should be interpreted as meaning: all holes on this assembly are to be three quarters of an inch in diameter, unless noted otherwise”. It is common to see the abbreviation UNO (unless noted otherwise) or UN (unless noted) in general notes. If any part of a print is subject to exception from a general note, a local note on a leader line should be present, if it is not the general note applies.
Notes may sometimes reference you to other documents. These documents may be quality assurance or fabrication requirements developed by your employer, or the employer’s customer. A note may also reference you to a recognized standard such as a welding or building code. For example, a local note may have a leader line with a note reading “see spec. A”, spec. A, or specification A, should be consulted to ensure that fabrication requirements are met.
