metal pipe railing
There are 3 primary material types of metal handrails commonly used in construction. Below is a list and summary of each type:
Steel – Material types available are
-ASTM A53 (Carbon Steel Alloy) Seamless and/or Welded in Nominal Pipe Size (NPS) of 1/8″ – 26″ of varying types and grades, Type E Grade B being most common. 1/2″ (0.84″ OD) – 3/4″ (1.05″ OD) – 1″ (1.315″ OD) – 1-1/4″ (1.66″ OD) – 1-1/2″ (1.9″ OD) – 2″ (2.375″ OD) – 2-1/2″ (2.875″) – 3″ (3.5″ OD) – 3-1/2″ (4″ OD) – 4″ (4.5″ OD) – 5″ (5.563″ OD) – 6″ (6.625″ OD) – 8″ (8.625″ OD) – 10″ (10.75″ OD)
-ASTM A500 (Carbon Steel Alloy) Cold Formed Welded and Seamless coming in round, square, and rectangular sizes. The 4 grades of ASTM 500 steel are A (45ksi), B (58ksi), C (62ksi), D (58ksi – heat treatment) and is based around tensile strength among other strength properties (composition, yield, elongation, etc). The sizes in this category are 88″ in size or less and with a wall thickness of 0.875″ or less. ASTM 500 tube for example, comes in common sizes of 1/2″ (0.84″ OD) – 3/4″ (1.05″ OD) – 1″ (1.315″ OD) – 1-1/4″ (1.66″ OD) – 1-1/2″ (1.9″ OD) – 2″ (2.375″ OD) – 3″ (3.5″ OD) – 3-1/2″ (4″ OD) – 4″ (4.5″ OD) – 5″ (5.563″ OD) – 6″ (6.625″ OD) – 8″ (8.625″ OD) – 10″ (10.75″ OD)
ASTM 501 (Carbon STeel Alloy) Hot Formed Welded and Seamless Pipe – This pipe is similar to ASTM 500 but a hot process is utilized in fabrication. Also the two grades are A (36,000psi) and B (50,000psi)
Connection types with the above materials is typically welded unless noted otherwise. A majority of the cost when fabricating a railing system involves the grinding and sanding needed to dress joints. Welded joints are commonly graded by Type 1, 2, 3 & 4 with type 1 having the fewest visual imperfections and type 4 having the most.
Steel pipe railing systems are either field painted or galvanized. Pipe or tubing can be supplied with either a black or galvanized finish. Field galvanizing is often deemed impractical due to workers protection, safety, and cost. When an engineer specifies galvanized pipe, either the pipe must be hot-dip galvanized after fabrication (which is often costly due to size limitations) or use pre-galvanized pipe with a zinc rich paint being applied in the field over welds and abrasions.
Extruded pipe and drawn tube are available in aluminum and are commonly used in pipe railing systems. The primary difference between pipe and tube is in dimensional tolerance and surface quality. Drawn tube pipe generally has tighter dimensional tolerance and fewer surface quality defects, while extruded pipe may not be as dimensionally strict and smooth. Welded pipe railing systems often do not require drawn tube material while flush fitting system assembled mechanically might. Tube-quality pipe is also used where an etched, anodized, or polished finish is specified.
The 2 common types of aluminum pipe material are ASTM B 429 Aluminum and ASTM B221 Aluminum.
Drawn Tube is commonly specified by ASTM B483 or ASTM B210.
Alloy 6063-T52 is commonly used in railing systems and can be bent without heating.
Alloy 6063-T832 has the smoothest surface and the best dimensional accuracy of almost any aluminum material; it is suitable for clear anodizing without discoloration. Alloy 6061-T6 has the same high strength as 6063T832 at less cost, but doesn’t bend as well and may tint yellowish when anodized. Aluminum handrail pipe commonly comes in two sizes, 1-1/4″ (1.66″ OD) and 1-1/2″ (1.9″ OD) and have wall thickness of 0.125″, 0.188″, and 0.25″. Aluminum rail connections are made by mitering, bending, welding, or using standard fittings.
Alloy 5356 or 4043 filler wire is used for mill finish aluminum. Alloy 5256 is used for rail that is to be anodized.
If appearance is important, welds are ground, polished, and blended; otherwise (especially in structural applications) the aluminum is left untouched at the welded joints. Welding removes temper and reduces strength within 1″ of a weld. Anodizing comes in clear and colored finishes, with bronze being quite popular. Anodizing finish provides a durable, visually appealing, weather resistant surface. An Architectural Class I finish has a minimum Anodic coating thickness of 0.7mils. An Architectural Class II finish has a minimum Anodic coating thickness of 0.4mils.
Clear anodized aluminum handrail
Handrails are corrosion and heat resistant iron-based alloy containing at least 16% chromium, along with nickel and other alloy elements. Stainless steel is grouped into numbers 200, 300, and 400. The stainless used for railing systems and other architectural applications is typically grade 304 and 316. Both grades are available in 304 pipe and tubing. The most economical form of stainless railing systems is welded tubing and is typically non-annealed, non-pickled, and non-pressure tested. This product is ASTM A554 (Welded Stainless Steel mechanical Tubing) is available in the same OD as stainless pipe, but can be had at a lower cost.
What is referred to as a #4 finish (general purpose bright polished finish) is most commonly used and readily available, but other finishes can be had like non-reflective mill finish and bright annealed.
#4 finish is easily matched in shop or field in terms of finish blending after welding or removal of surface blemishes.
Handrails posts can be anchored on horizontal surfaces by round flange and acnhor, coring and grouting, slip fitted metal socket, and welded to anchored plate.
Some common types of post bases are flat flange, raised flange, tapered flat flange, rectangular flat flange. Connections can be either welded or non welded (mechanically attached with fittings).
Wall-mounted handrails are commonly attached to walls with handrail bracket; extruded, formed, cast, or machined.