A usual setup would be a proxy which downloads the updates from Red Hat and provides them to your local servers. This way only one server has to be connected to the internet. Your question is not clear, whether there is generally no internet access or only the mentioned servers are not allowed to access the internet.
Some proxy solutions also allow to download the patches with your desktop PC or whatever, put them on a proxy server and then publish them to your local network.
The Red Hat specific products are spacewalk and the Red Hat Network commercial products. This page has also some more explanations about the topic.
This is easier and more scalable as installing it manually on each server.
You could also search serverfault for patch management, spacewalk, rhel updates and get some more info on the topic.
Found this in another forum:
To update packages to a system without Internet connectivity, you need to download the ISO and then mount it locally. To download iso's, please check below given steps:
Log into your RHN account.
select your desired channel under the "Channels" tab.
then click "Easy ISOs" on the left or the "Download" link inside your selected channel.
For details, please follow the below kbase, http://kbase.redhat.com/faq/FAQ_58_1500.shtm
Once you download the iso's, follow the below given steps:
Create directories to mount the iso file.
mkdir -p /cdrom/iso
Mount the iso as loopback device.
mount -o loop <iso-name> /cdrom/iso
Replace with the iso file.
Create a repository. The createrepo package needs to be installed on the system in order to run the following commands. createrepo is an optional package and is not installed by default.
yum clean all
Create a file /etc/yum.repos.d/file.repo as follows:
[RHEL 5 Repository]
Running yum should now work with the iso file as the source.
For details, please check following kbase, http://kbase.redhat.com/faq/FAQ_103_10415.shtm (as archived by Wayback machine).
Let us know if you have any further queries.